Investigate/perform upgrade to Geth 1.8.1

[pedropombeiro]

Problem

Geth 1.8.1 was released today. It contains many improvements that are important for us, and by upgrading to 1.8.1 we render some patches redundant (namely 0011-geth-17-whisperv6-70fbc87.patch which ported Whisper v6 to our fork), making future maintenance easier.

Implementation

Investigate breaking changes in 1.8.1 to determine what work must be done as part of the upgrade. Perform upgrade.

Breaking changes checklist

• Discovery v4 and v5 have been merged to use the same UDP port (30303 by default). If you are doing manual peer management and using the light client, you may need to ensure your v1.8.0 clients are pointed to port 30303 and not 30304 as previously.
• Trie pruning is enabled on all --syncmode variations (including --syncmode=full). If you are running an archive node where you would like to retain all historical data, you should disable pruning via --gcmode=archive.
• Only the latest 128 tries are kept in memory, most tries are garbage collected. If you are running a block explorer or other service relying on transaction tracing without an archive node (--gcmode=archive), you need to trace within this window! Alternatively, specify the reexec: 12345 tracer option to allow regenerating historical state; and ideally switch to chain tracing which amortizes overhead across all traced blocks.
• Native events rely on modifications to internal go-ethereum types within generated code. If you are using wrappers generated prior to v1.8.0, you will need to regenerate them to be compatible with the new code base.
• The HTTP/WS RPC endpoint was extended with DNS rebind protection. If you are running an RPC endpoint addressed by name rather than IP, run with --rpcvhost=your.domain to continue accepting remote requests.

Acceptance Criteria

• The different make targets work as expected (e.g. make ci, make statusgo-android, etc)
• TBD

Notes

This GHI only makes sense to start once #660 is merged.

TDB

Future Steps

• Upgrade bootnodes and mailserver cluster with new version.
• TBD

[dshulyak]

The GasLimit and GasUsed fields of blocks and transactions have type uint64 instead of *big.Int. This is a breaking API change. (#15466)

this should require changes in tx manager code and fake backend for tests

[pedropombeiro]

Random notes as I'm going through the migration:

• Using localhost in the URL causes DNS rebinding protection to kick in and fail the HTTP request. Solution is to either use IP or add localhost as an exception in the node config.
• go-ethereum duktape patch might be accepted upstream (mentioned in https://gitter.im/olebedev/go-duktape)
• E2E tests seem flaky (passed locally but failed on Travis CI):

go test -timeout 20m ./t/e2e/whisper/... -network=
--- FAIL: TestWhisperMailboxTestSuite (23.35s)
    --- FAIL: TestWhisperMailboxTestSuite/TestRequestMessagesInGroupChat (15.29s)
	Error Trace:	whisper_mailbox_test.go:250
	Error:      	Not equal: 
	            	expected: 1
	            	actual: 0