Fix some tag bugs

Bad meta and custom_name threw giant stacktraces needlessly.
Merge pull request #676 from Morphan1/master

Create features for non-existing features that don't exist
Merge pull request #675 from mcmonkey4eva/master

Pull request for tiny fixes
Conform to Denizen standards

Hurray for +1 -1 slots
Allow "player clicks" in "player (<click type>) clicks block"