Add source argument to Hurt

A way to give a damage source entity... does not always work, all sorts
of weird potential issues with the way MC handles damage
Also fix meta, catch errors, ...
Patch definition bugs

- Definitions wouldn't escape <tags>... now they do
- Invalid def tags would throw weird errors... now throw correct errors,
and only when needed.
minor fixes again

- list.exclude acting weird
- anchor throwing weird errors...
Add server.list_permission_groups

Added at request
(No other minor changes dumped in with this one 0.o)
Merge pull request #756 from mcmonkey4eva/master

Pull request for security and weirdness