Refs #1771

ADR: https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-044-lite-client-with-weak-subjectivity.md

## Commits:

* add Verifier and VerifyCommitTrusting

* add two more checks

make trustLevel an option

* float32 for trustLevel

* check newHeader time

* started writing lite Client

* unify Verify methods

* ensure h2.Header.bfttime < h1.Header.bfttime + tp

* move trust checks into Verify function

* add more comments

* more docs

* started writing tests

* unbonding period failures

* tests are green

* export ErrNewHeaderTooFarIntoFuture

* make golangci happy

* test for non-adjusted headers

* more precision

* providers and stores

* VerifyHeader and VerifyHeaderAtHeight funcs

* fix compile errors

* remove lastVerifiedHeight, persist new trusted header

* sequential verification

* remove TrustedStore option

* started writing tests for light client

* cover basic cases for linear verification

* bisection tests PASS

* rename BisectingVerification to SkippingVerification

* refactor the code

* add TrustedHeader method

* consolidate sequential verification tests

* consolidate skipping verification tests

* rename trustedVals to trustedNextVals

* start writing docs

* ValidateTrustLevel func and ErrOldHeaderExpired error

* AutoClient and example tests

* fix errors

* update doc

* remove ErrNewHeaderTooFarIntoFuture

This check is unnecessary given existing a) ErrOldHeaderExpired b)
h2.Time > now checks.

* return an error if we're at more recent height

* add comments

* add LastSignedHeaderHeight method to Store

I think it's fine if Store tracks last height

* copy over proxy from old lite package

* make TrustedHeader return latest if height=0

* modify LastSignedHeaderHeight to return an error if no headers exist

* copy over proxy impl

* refactor proxy and start http lite client

* Tx and BlockchainInfo methods

* Block method

* commit method

* code compiles again

* lite client compiles

* extract updateLiteClientIfNeededTo func

* move final parts

* add placeholder for tests

* force usage of lite http client in proxy

* comment out query tests for now

* explicitly mention tp: trusting period

* verify nextVals in VerifyHeader

* refactor bisection

* move the NextValidatorsHash check into updateTrustedHeaderAndVals

+ update the comment

* add ConsensusParams method to RPC client

* add ConsensusParams to rpc/mock/client

* change trustLevel type to a new cmn.Fraction type

+ update SkippingVerification comment

* stress out trustLevel is only used for non-adjusted headers

* fixes after Fede's review

Co-authored-by: Federico Kunze <31522760+fedekunze@users.noreply.github.com>

* compare newHeader with a header from an alternative provider

* save pivot header

Refs https://github.com/tendermint/tendermint/pull/3989#discussion_r349122824

* check header can still be trusted in TrustedHeader

Refs https://github.com/tendermint/tendermint/pull/3989#discussion_r349101424

* lite: update Validators and Block endpoints

- Block no longer contains BlockMeta
- Validators now accept two additional params: page and perPage

* make linter happy

and EventDataNewBlockHeader

## Issue:

    Removed BlockMeta in ResultBlock in favor of BlockId for /block
    Added block_size to BlockMeta this is reflected in /blockchain

fixes #3188

added breaking as some clients may be using header from blockmeta instead of block in /block

## Commits:

* cleanup block path

Remove duplication of data in `/block`

fixes #3188

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* Remove duplication of data in `/block`

- Created a secondary type to be used for /block

fixes #3188

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* remove commented out code

* fix ci

* add changelog_pending entry

* remove extra variable

* update swagger

* change int to uint for blocksize

* fix swagger

* remove extensive comments

* update changelog

* fix conflicts after merge

* use int for BlockSize and NumTxs in BlockMeta

- with 99.9% guarantee, the size of either will never reach int32
- most of the Go "Size" stdlib functions return int

* Removal of TotalTx & NumTx

- Removed totalTx and numTx

closes #2521

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* abci proto changes

* proto number fix

* txfilter_test fix

* comments on PR

* further changes

* bring back metrics

* fix indexer

* fix TestBlockMaxDataBytes and TestBlockMaxDataBytesUnknownEvidence

* indexer service back to header

* statistics.go fix

* fix ci

* listen for blocks, not headers

to be able to record txs throughput

* fix TestNetworkNewBlock

* fix tests

* fix tests in types package

* fixes after Anton's review

* fix tests

* bring back `consensus_total_txs` metric

I mistakenly thought it was removed.

* improve changelog

* remove LastBlockTotalTx from state

* docs: remove getNumTxs from BeginBlock Java example

* upadtes in grpc Marshal and unmarshal

* update comments

make BlockMeta Header a non-pointer

Refs #693

This reverts commit d02c5d1e30.

This reverts commit 96a3502