add element.matches[regex], more meta work

- we apparently did not have a regex matcher for tags yet somehow
- more tag groups, yay
Fix some YAML imperfections, further meta work

- tag groups and mechanisms!
- YAML command would duplicate if create was called repeatedly for the
same ID, and gave some useless debug.
Merge pull request #703 from mcmonkey4eva/master

Pull request for excessive meta work