Minor code cleanup.
Merge branch 'master' into gc-proto-v1
Tweak comment.
Merge branch 'master' into gc-proto-v1
Checkpoint.
Tweak comment.
Merge branch 'master' into gc-proto-v1

Conflicts:
	lib/bud.rb
Bugfixes for TupleStruct#source_address.
Implement TupleStruct#hash and TupleStruct#eql?

These should probably have been implemented all along.
Add a test case for TupleStruct#source_address.