* swarm: Added lightnode flag
Added --lightnode command line parameter
Added LightNode to Handshake message
* swarm/config: Fixed variable naming
* cmd/swarm: Changed BoolTFlag to BoolFlag for SwarmLightNodeEnabled
* swarm/network: Changed logging
* swarm/network: Changed protocol version testing
* swarm/network: Renamed DefaultNetworkID variable to TestProtocolNetworkID
* swarm/network: Bumped protocol version
* swarm/network: Changed LightNode handhsake test to table driven
* swarm/network: Changed back TestProtocolVersion to 5 for now
* swarm/network: Moved the test configuration inside the test function scope
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
