* swarm/network: integrity on incoming known chunks
* swarm/network: fix integrity check for incoming chunks
* swarm/storage: imrpoved integrity checking on chunks
* dbstore panics on corrupt chunk entry an prompts user to run cleandb
* memstore adds logging for garbage collection
* dbstore refactor item delete. correct partial deletes in Get
* cmd/swarm: added cleandb subcommand

go get github.com/gordonklaus/ineffassign
ineffassign .

* cmd/bzzd: add missing p2p/discovery flags
* cmd/bzzd: fix two bugs crashing bzzd if bootnodes flag given
* cmd/bzzd: make no swap default, renamed flag bzznoswap->bzzswap
* internal/web3ext: correct methods for bzz IPC module
* cmd/bzzd: ethapi param not mandatory. Warning if no blockchain
* cmd/bzzd: correct default IPC modules in help string
* cmd/utils: fix help description for networkId - add Ropsten
* cmd/bzz, swarm/api, swarm/network: add swarm networkId flag
* cmd/bzzd: change nosync flag to sync and BootTFlag

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