The evm compile command implements a simple assembly language that compiles to
EVM bytecode.

This significantly reduces the dependency closure of ethclient, which no
longer depends on core/vm as of this change.

All uses of vm.Logs are replaced by []*types.Log. NewLog is gone too,
the constructor simply returned a literal.

All code outside of cmd/ is licensed as LGPL. The headers
now reflect this by calling the whole work "the go-ethereum library".