* accounts/abi: handle named ouputs prefixed with underscores

* accounts/abi: handle collinding outputs for struct unpacks

* accounts: handle purely underscore output names

+ adding missing comments
+ small cleanups which won't significantly change
  function body.
+ unify Method receiver name

+ The event slice unpacker doesn't correctly extract element from the
slice. The indexed arguments are not ignored as they should be
(the data offset should not include the indexed arguments).

+ The `Elem()` call in the slice unpack doesn't work.
The Slice related tests fails because of that.

+ the check in the loop are suboptimal and have been extracted
out of the loop.

+ extracted common code from event and method tupleUnpack

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.

Implementation of basic event parsing and its input types. This
separates methods and events and fixes an issue with go type parsing and
validation.

Added calling mechanism and return value parsing

I forgot to update one instance of "go-ethereum" in commit 3f047be5.

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