You can now specify `null` as a way of saying "not interested in this
topic, match all". core.Filter assumes the zero'd address to be the
wildcard. JSON rpc assumes empty strings to be wildcards.

All nonce error handling has been moved to the worker

When worker encounters a gas limit error, subsequent txs should be
ignored from that particular account. This will prevent:

1. Nonce errors been thrown all around
2. The "Known tx" error. Closes #719
3. Repeated contract address. Closes #731

admin.StopRPC added to console

cmd/geth, cmd/utils: add cli flags for pprof and whisper

Merge branch 'frontier/natspec' of https://github.com/ethersphere/go-ethereum into ethersphere-frontier/natspec

- simplify resolver and tests
- added missing test for KeyToUrl
- fix notice error message and its test with !%x(MISSING)
- natspec test: insertTx modified - does not prepend 0x to contract address
- disable networking in e2e test

- add resolver tests and fix resolver to pass
- statereg constructor fixed
- comments added to natspec plus docserver integration for natspec userdoc fetching

- statereg methods move to natspec/resolver/docserver
- fix failing test on invalid js input