Port mapper auto discovery used to run immediately after parsing the
--nat flag, giving it a slight performance boost. But this is becoming
inconvenient because we create node.Node for all geth operations
including account management and bare chain interaction. Delay
autodiscovery until the first use instead, which avoids any network
interaction until the node is actually started.

cmd, eth: drop the blockchain version from cli/eth configs

miner: set tx index logs

rpc: format filter ID according to spec for quantities

core/types, ethclient: fix broken subscriptions

ethereum, ethclient: add SyncProgress API endpoint

cmd/evm, cmd/geth, cmd/utils: move version handling to cmd/utils

miner: Prevent attempts to close nil quit channel in agent (fixes #2948)

Transaction pool optimizations

contracts/ens: Replace setOwner with setSubnodeOwner per EIP137

swarm: plan bee for content storage and distribution on web3

Small docker run example for main README

This change imports the Swarm protocol codebase. Compared to the 'swarm'
branch, a few mostly cosmetic changes had to be made:

* The various redundant log message prefixes are gone.
* All files now have LGPLv3 license headers.
* Minor code changes were needed to please go vet and make the tests
  pass on Windows.
* Further changes were required to adapt to the go-ethereum develop
  branch and its new Go APIs.

Some code has not (yet) been brought over:

* swarm/cmd/bzzhash: will reappear as cmd/bzzhash later
* swarm/cmd/bzzup.sh: will be reimplemented in cmd/bzzup
* swarm/cmd/makegenesis: will reappear somehow
* swarm/examples/album: will move to a separate repository
* swarm/examples/filemanager: ditto
* swarm/examples/files: will not be merged
* swarm/test/*: will not be merged
* swarm/services/swear: will reappear as contracts/swear when needed

contracts/release: move package release to contracts/

contracts/ens: regenerate binding with solc v0.3.6

contracts/chequebook: fix possible reentrancy bug in chequebook contract

Godeps: update golang.org/x/...

This change also deletes generator.go, moving the only interesting line
in it into release.go. The binding has been regenerated with abigen from
develop and solc v0.3.6.

contracts/ens: Add ENS contract binding

contracts/chequebook: add chequebook contract wrapper

The wrapper code is adapted from the swarm/services/chequebook package
with the following mostly cosmetic changes:

* The code now uses the new Go API interfaces to query balances. Some
  minor functional changes were required to make this work.
* The package no longer depends on swarm/services/swap/swap. References
  to swap.Promise are replaced by interface{}, the base type of Promise.
  This is temporary.
* The contract wrapper has been regenerated with latest abigen
  and solc v0.3.6.
* There is a new generator that creates the 'deployed code' variable.
* Documentation comments now follow the recommended godoc style.
* [CHEQUEBOOK] log prefixes are gone.
* LGPL license headers have been added to all files.