return an error if we fail to parse external IP

Escape paths in config template

```
I[06-08|11:51:57.234] Getting UPNP external address                module=p2p
I[06-08|11:51:58.867] Got UPNP external address                    module=p2p address=
```

Fixes #1717

```
I[06-08|11:51:56.952] Starting multiAppConn                        module=proxy impl=multiAppConn
I[06-08|11:51:56.952] Starting localClient                         module=abci-client connection=query impl=localClient
I[06-08|11:51:56.952] Starting localClient                         module=abci-client connection=mempool impl=localClient
I[06-08|11:51:56.952] Starting localClient                         module=abci-client connection=consensus impl=localClient
I[06-08|11:51:56.952] ABCI Handshake                               module=consensus appHeight=0 appHash=
I[06-08|11:51:56.952] ABCI Replay Blocks                           module=consensus appHeight=0 storeHeight=0 stateHeight=0
I[06-08|11:51:57.053] Completed ABCI Handshake - Tendermint and App are synced module=consensus appHeight=0 appHash=
I[06-08|11:51:57.053] This node is a validator                     module=consensus addr=6816B5D9BAC32A3CDF07884D9D3D2650694C371D pubKey=PubKeyEd25519{27A40CD032DD2467342D0CF27C5EC92052D966FEC714B6CF2F3BF3146AFD0D51}
I[06-08|11:51:57.234] Starting Node                                module=main impl=Node
I[06-08|11:51:57.234] Starting EventBus                            module=events impl=EventBus
I[06-08|11:51:57.234] Local listener                               module=p2p ip=:: port=46656
I[06-08|11:51:57.234] Getting UPNP external address                module=p2p
I[06-08|11:51:58.867] Got UPNP external address                    module=p2p address=
I[06-08|11:51:58.867] Starting DefaultListener                     module=p2p impl=Listener(@<nil>:46656)
I[06-08|11:51:58.867] P2P Node ID                                  module=main ID=3629b516392e494ae717ac4c6a1ea7eb0fe421c3 file=/home/tpb/.tendermint/config/node_key.json
I[06-08|11:51:58.868] Add our address to book                      module=p2p book=/home/tpb/.tendermint/config/addrbook.json addr=null
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x38 pc=0x89fb86]

goroutine 1 [running]:
github.com/tendermint/tendermint/p2p.(*NetAddress).String(0x0, 0xc96e24, 0x17)
	/home/tpb/code/go/src/github.com/tendermint/tendermint/p2p/netaddress.go:171 +0x26
github.com/tendermint/tendermint/p2p/pex.(*addrBook).AddOurAddress(0xc420190620, 0x0)
	/home/tpb/code/go/src/github.com/tendermint/tendermint/p2p/pex/addrbook.go:160 +0x116
github.com/tendermint/tendermint/node.(*Node).OnStart(0xc420286d00, 0xc4201b8010, 0xd)
	/home/tpb/code/go/src/github.com/tendermint/tendermint/node/node.go:402 +0x547
github.com/tendermint/tendermint/vendor/github.com/tendermint/tmlibs/common.(*BaseService).Start(0xc420286d00, 0xe51c40, 0xc42000bd40)
	/home/tpb/code/go/src/github.com/tendermint/tendermint/vendor/github.com/tendermint/tmlibs/common/service.go:130 +0x3bd
github.com/tendermint/tendermint/cmd/tendermint/commands.NewRunNodeCmd.func1(0xc42022e000, 0xc4200acdc0, 0x0, 0x1, 0x0, 0x0)
	/home/tpb/code/go/src/github.com/tendermint/tendermint/cmd/tendermint/commands/run_node.go:58 +0xfe
github.com/tendermint/tendermint/vendor/github.com/spf13/cobra.(*Command).execute(0xc42022e000, 0xc4200acda0, 0x1, 0x1, 0xc42022e000, 0xc4200acda0)
	/home/tpb/code/go/src/github.com/tendermint/tendermint/vendor/github.com/spf13/cobra/command.go:762 +0x468
github.com/tendermint/tendermint/vendor/github.com/spf13/cobra.(*Command).ExecuteC(0x1289280, 0xbbdda0, 0xc420015e01, 0xc4201bc640)
	/home/tpb/code/go/src/github.com/tendermint/tendermint/vendor/github.com/spf13/cobra/command.go:852 +0x30a
github.com/tendermint/tendermint/vendor/github.com/spf13/cobra.(*Command).Execute(0x1289280, 0xc4201bc640, 0xc420015e98)
	/home/tpb/code/go/src/github.com/tendermint/tendermint/vendor/github.com/spf13/cobra/command.go:800 +0x2b
github.com/tendermint/tendermint/vendor/github.com/tendermint/tmlibs/cli.Executor.Execute(0x1289280, 0xde5798, 0x2, 0xc4200332c0)
	/home/tpb/code/go/src/github.com/tendermint/tendermint/vendor/github.com/tendermint/tmlibs/cli/setup.go:89 +0x4e
main.main()
	/home/tpb/code/go/src/github.com/tendermint/tendermint/cmd/tendermint/main.go:45 +0x24d
```

Update description of seed and persistent peer nodes

docs to markdown

Release/v0.20.0

docs: Add BSD install script

Fix race when mutating MConnConfig

Bucky/abci fixes

Instead of mutating the passed in MConnConfig part of P2PConfig we just
use the default and override the values, the same as before as it was
always the default version. This is yet another good reason to not embed
information and access to config structs in our components and will go
away with the ongoing refactoring in #1325.

Update ABCI for new PubKey type and changes to BeginBlock and InitChain