For more information about this light client mode, read
https://hackmd.io/s/HJy7jjZpm

This replaces the GasSlowStep constant with params.ExpGas.
Both constants have value 10.

This PR adds a new fork which disables EIP-1283. Internally it's called Petersburg,
but the genesis/config field is ConstantinopleFix.

The block numbers are:

    7280000 for Constantinople on Mainnet
    7280000 for ConstantinopleFix on Mainnet
    4939394 for ConstantinopleFix on Ropsten
    9999999 for ConstantinopleFix on Rinkeby (real number decided later)

This PR also defaults to using the same ConstantinopleFix number as whatever
Constantinople is set to. That is, it will default to mainnet behaviour if ConstantinopleFix
is not set.This means that for private networks which have already transitioned
to Constantinople, this PR will break the network unless ConstantinopleFix is
explicitly set!

* tests: tune flaky tests that error in travis occasionally

* tests: formatting

* Initial work on a graphql API

* Added receipts, and more transaction fields.

* Finish receipts, add logs

* Add transactionCount to block

* Add types  and .

* Update Block type to be compatible with ethql

* Rename nonce to transactionCount in Account, to be compatible with ethql

* Update transaction, receipt and log to match ethql

* Add  query operator, for a range of blocks

* Added ommerCount to Block

* Add transactionAt and ommerAt to Block

* Added sendRawTransaction mutation

* Add Call and EstimateGas to graphQL API

* Refactored to use hexutil.Bytes instead of HexBytes

* Replace BigNum with hexutil.Big

* Refactor call and estimateGas to use ethapi struct type

* Replace ethgraphql.Address with common.Address

* Replace ethgraphql.Hash with common.Hash

* Converted most quantities to Long instead of Int

* Add support for logs

* Fix bug in runFilter

* Restructured Transaction to work primarily with headers, so uncle data is reported properly

* Add gasPrice API

* Add protocolVersion API

* Add syncing API

* Moved schema into its own source file

* Move some single use args types into anonymous structs

* Add doc-comments

* Fixed backend fetching to use context

* Added (very) basic tests

* Add documentation to the graphql schema

* Fix reversion for formatting of big numbers

* Correct spelling error

* s/BigInt/Long/

* Update common/types.go

* Fixes in response to review

* Fix lint error

* Updated calls on private functions

* Fix typo in graphql.go

* Rollback ethapi breaking changes for graphql support
Co-Authored-By: Arachnid <arachnid@notdot.net>

receipts may be null for very short time in some condition. For this case, we should not add the null value into cache. Because you will not get the right result if you keep requesting that receipt.

* swarm/network: fix data race in stream.(*Peer).handleOfferedHashesMsg()

handleOfferedHashesMsg() contained a data race:
- read => in a goroutine, call to c.batchDone()
- write => in the main thread, write to c.sessionAt

c.batchDone() contained a call to c.AddInterval(). Client was a value
receiver for AddInterval. So on c.AddInterval() call the whole client
struct got copied (read) while one of its field was modified in
handleOfferedHashesMsg() (write).

fixes ethersphere/go-ethereum#1086

* swarm/network: simplify some trivial statements

core, light: get rid of the dual mutexes, hard to reason with

* swarm/network: fix skipped tests related to suggestPeer

* swarm/network: rename depth to radius

* swarm/network: uncomment assertHealth and improve comments

* swarm/network: remove commented code

* swarm/network: kademlia suggestPeer algo correction

* swarm/network: kademlia suggest peer

 * simplify suggest Peer code
 * improve peer suggestion algo
 * add comments
 * kademlia testing improvements
   * assertHealth -> checkHealth (test helper)
   * testSuggestPeer -> checkSuggestPeer (test helper)
   * remove testSuggestPeerBug and TestKademliaCase

* swarm/network: kademlia suggestPeer cleanup, improved comments

* swarm/network: minor comment, discovery test default arg

* cmd/swarm/swarm-snapshot: add binary to create network snapshots

* cmd/swarm/swarm-snapshot: refactor and extend tests

* p2p/simulations: remove unused triggerChecks func and fix linter

* internal/cmdtest: raise the timeout for killing TestCmd

* cmd/swarm/swarm-snapshot: add more comments and other minor adjustments

* cmd/swarm/swarm-snapshot: remove redundant check in createSnapshot

* cmd/swarm/swarm-snapshot: change comment wording

* p2p/simulations: revert Simulation.Run from master

https://github.com/ethersphere/go-ethereum/pull/1077/files#r247078904

* cmd/swarm/swarm-snapshot: address pr comments

* swarm/network/simulations/discovery: removed snapshot write to file

* cmd/swarm/swarm-snapshot, swarm/network/simulations: removed redundant connection event check, fixed lint error

fixes: ethersphere/go-ethereum#1117

* Update copyright

2018 -> 2019

* Update copyright

2018 -> 2019

params: postpone Constantinople due to net SSTORE reentrancy

* swarm/pot: refactored pot.remove(), updated comments

* swarm/pot: comments updated

* swarm/network: eachBin now starts at kaddepth for nn

* swarm/network: fix Kademlia.EachBin

* swarm/network: fix kademlia.EachBin

* swarm/network: correct EachBin implementation according to requirements

* swarm/network: less addresses simplified tests

* swarm: calc kad depth outside loop in EachBin test

* swarm/network: removed printResults

* swarm/network: cleanup imports

* swarm/network: remove kademlia.EachBin; fix RequestSubscriptions and add unit test

* swarm/network/stream: address PR comments

* swarm/network/stream: package-wide subscriptionFunc

* swarm/network/stream: refactor to kad.EachConn

* core, eth: fix database version

* eth: polish error message