Make RPCError an actual error and don't swallow its companion data

https://github.com/tendermint/tendermint/issues/762#issuecomment-338276055
```
E[10-19|04:52:38.969] Stopping peer for error                      module=p2p peer="Peer{MConn{178.62.46.14:46656} B14916FAF38A out}" err="Error: runtime error: invalid memory address or nil pointer dereference\nStack: goroutine 529485 [running]:\nruntime/debug.Stack(0xc4355cfb38, 0xb463e0, 0x11b1c30)\n\t/usr/local/go/src/runtime/debug/stack.go:24 +0xa7\ngithub.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/p2p.(*MConnection)._recover(0xc439a28870)\n\t/home/ubuntu/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/p2p/connection.go:206 +0x6e\npanic(0xb463e0, 0x11b1c30)\n\t/usr/local/go/src/runtime/panic.go:491 +0x283\ngithub.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/blockchain.(*bpPeer).decrPending(0x0, 0x381)\n\t/home/ubuntu/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/blockchain/pool.go:376 +0x22\ngithub.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/blockchain.(*BlockPool).AddBlock(0xc4200e4000, 0xc4266d1f00, 0x40, 0xc432ac9640, 0x381)\n\t/home/ubuntu/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/blockchain/pool.go:215 +0x139\ngithub.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/blockchain.(*BlockchainReactor).Receive(0xc42050a780, 0xc420257740, 0x1171be0, 0xc42ff302d0, 0xc4384b2000, 0x381, 0x1000)\n\t/home/ubuntu/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/blockchain/reactor.go:160 +0x712\ngithub.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/p2p.createMConnection.func1(0x11e5040, 0xc4384b2000, 0x381, 0x1000)\n\t/home/ubuntu/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/p2p/peer.go:334 +0xbd\ngithub.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/p2p.(*MConnection).recvRoutine(0xc439a28870)\n\t/home/ubuntu/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/p2p/connection.go:475 +0x4a3\ncreated by github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/p2p.(*MConnection).OnStart\n\t/home/ubuntu/go/src/github.com/cosmos/gaia/vendor/github.com/tendermint/tendermint/p2p/connection.go:170 +0x187\n"
```

all, state: unexpose GenesisDoc, ChainID fields make them accessor methods

rpc/client: use compile time assertions instead of methods

Fixes https://github.com/tendermint/tendermint/issues/747
Updates https://github.com/tendermint/tendermint/issues/693

* Document the unmentioned limits for ConsensusParams.Validate()
* Make the limit for ConsensusParams.BlockSizeParams.MaxBytes
clear at 100MiB

https://github.com/tendermint/tendermint/pull/676#discussion_r144411458

also remove the comment

```
jaekwon
Yeah we should definitely expose ChainID.
ConsensusParams is small enough, we can just write it.
```
https://github.com/tendermint/tendermint/pull/676#discussion_r144123203

- remove state#GenesisDoc() method

Fixes #671

Unexpose GenesisDoc and ChainID fields to avoid them being
serialized to the DB on every block write/state.Save()

A GenesisDoc can now be alternatively written to the state's
database, by serializing its JSON as a value of key "genesis-doc".

There are now accessors and a setter for these attributes:
- state.GenesisDoc() (*types.GenesisDoc, error)
- state.ChainID() (string, error)
- state.SetGenesisDoc(*types.GenesisDoc)

This is a breaking change since it changes how the state's
serialization and requires that if loading the GenesisDoc entirely
from the database, you'll need to set its value in the database
as the GenesisDoc's JSON marshaled bytes.

types/heartbeat: test all Heartbeat functions

support historical abci queries

Release/0.11.1

[docs: typo fix] add missing "have"

[docs:typo fix] remove misplaced "the"

Leaving out params crashes tm rpc

https://github.com/tendermint/tendermint/pull/724#issuecomment-335362927

https://github.com/tendermint/tendermint/pull/724#issuecomment-335316484

so they can be used in rpc/core/types/responses.go.

```
So, it seems like we could use the actual structs here, but we don't want to have to import consensus to get them, as then clients are importing too much crap. So probably we should move some types from consensus into consensus/types so we can import.

Will these raw messages be identical to:

type ResultDumpConsensusState struct {
  RoundState cstypes.RoundState
  PeerRoundStates map[string]cstypes.PeerRoundState
}
```
https://github.com/tendermint/tendermint/pull/724#discussion_r143598193

Before:

```
{
  "jsonrpc": "2.0",
  "id": "",
  "result": {
    "round_state": "RoundState{\n  H:10 R:0 S:RoundStepNewHeight\n  StartTime:     2017-10-09 13:07:24.841134374 +0400 +04\n  CommitTime:    2017-10-09 13:07:23.841134374 +0400 +04\n  Validators:    ValidatorSet{\n      Proposer: Validator{EF243CC0E9B88D0161D24D733BDE9003518CEA27 {PubKeyEd25519{2E0B9301334FCDAB193D514022F81BA09BBEC028685C96602BE9DD0BD4F9E202}} VP:10 A:0}\n      Validators:\n        Validator{EF243CC0E9B88D0161D24D733BDE9003518CEA27 {PubKeyEd25519{2E0B9301334FCDAB193D514022F81BA09BBEC028685C96602BE9DD0BD4F9E202}} VP:10 A:0}\n    }\n  Proposal:      \u003cnil\u003e\n  ProposalBlock: nil-PartSet nil-Block\n  LockedRound:   0\n  LockedBlock:   nil-PartSet nil-Block\n  Votes:         HeightVoteSet{H:10 R:0~0\n      VoteSet{H:10 R:0 T:1 +2/3:\u003cnil\u003e BA{1:_} map[]}\n      VoteSet{H:10 R:0 T:2 +2/3:\u003cnil\u003e BA{1:_} map[]}\n    }\n  LastCommit: VoteSet{H:9 R:0 T:2 +2/3:947F67A7B85439AF2CD5DFED376C51AC7BD67AEE:1:365E9983E466 BA{1:X} map[]}\n  LastValidators:    ValidatorSet{\n      Proposer: Validator{EF243CC0E9B88D0161D24D733BDE9003518CEA27 {PubKeyEd25519{2E0B9301334FCDAB193D514022F81BA09BBEC028685C96602BE9DD0BD4F9E202}} VP:10 A:0}\n      Validators:\n        Validator{EF243CC0E9B88D0161D24D733BDE9003518CEA27 {PubKeyEd25519{2E0B9301334FCDAB193D514022F81BA09BBEC028685C96602BE9DD0BD4F9E202}} VP:10 A:0}\n    }\n}",
    "peer_round_states": []
  }
}
```

After:

```
{
  "jsonrpc": "2.0",
  "id": "",
  "result": {
    "round_state": {
      "Height": 1691,
      "Round": 0,
      "Step": 1,
      "StartTime": "2017-10-09T14:08:09.129491764+04:00",
      "CommitTime": "2017-10-09T14:08:08.129491764+04:00",
      "Validators": {
        "validators": [
          {
            "address": "EF243CC0E9B88D0161D24D733BDE9003518CEA27",
            "pub_key": {
              "type": "ed25519",
              "data": "2E0B9301334FCDAB193D514022F81BA09BBEC028685C96602BE9DD0BD4F9E202"
            },
            "voting_power": 10,
            "accum": 0
          }
        ],
        "proposer": {
          "address": "EF243CC0E9B88D0161D24D733BDE9003518CEA27",
          "pub_key": {
            "type": "ed25519",
            "data": "2E0B9301334FCDAB193D514022F81BA09BBEC028685C96602BE9DD0BD4F9E202"
          },
          "voting_power": 10,
          "accum": 0
        }
      },
      "Proposal": null,
      "ProposalBlock": null,
      "ProposalBlockParts": null,
      "LockedRound": 0,
      "LockedBlock": null,
      "LockedBlockParts": null,
      "Votes": {},
      "CommitRound": -1,
      "LastCommit": {},
      "LastValidators": {
        "validators": [
          {
            "address": "EF243CC0E9B88D0161D24D733BDE9003518CEA27",
            "pub_key": {
              "type": "ed25519",
              "data": "2E0B9301334FCDAB193D514022F81BA09BBEC028685C96602BE9DD0BD4F9E202"
            },
            "voting_power": 10,
            "accum": 0
          }
        ],
        "proposer": {
          "address": "EF243CC0E9B88D0161D24D733BDE9003518CEA27",
          "pub_key": {
            "type": "ed25519",
            "data": "2E0B9301334FCDAB193D514022F81BA09BBEC028685C96602BE9DD0BD4F9E202"
          },
          "voting_power": 10,
          "accum": 0
        }
      }
    },
    "peer_round_states": {
      "75EC8F15D244A421202F9725CD4DE509EE50303670310CF7530EF25E2B7C524B": {
        "Height": 1691,
        "Round": 0,
        "Step": 1,
        "StartTime": "2017-10-09T14:08:08.563251997+04:00",
        "Proposal": false,
        "ProposalBlockPartsHeader": {
          "total": 0,
          "hash": ""
        },
        "ProposalBlockParts": null,
        "ProposalPOLRound": -1,
        "ProposalPOL": null,
        "Prevotes": null,
        "Precommits": null,
        "LastCommitRound": 0,
        "LastCommit": null,
        "CatchupCommitRound": -1,
        "CatchupCommit": null
      }
    }
  }
}
```

Updates https://github.com/tendermint/tendermint/issues/693

* Adjusted Heartbeat.Copy to return nil on
trying to copy a nil value instead of panicking.
* Also documented that WriteSignBytes panics
if the Heartbeat is nil.

restore rpc/lib readme as doc.go (Refs #710) [ci skip]

I don't want to lose any documentation. Correct me if I am wrong, but we
don't have this docs anywhere else.