Covered `this` up in most of the editor, plugins and test code.
Strange `wym._wym` to just `wym`.
Some fixes after covering `this` up.
Merge branch 'master' into issue_569

Conflicts:
	src/wymeditor/editor/base.js
Fix comment.
Fix var statements in hovertools plugin.
Merge pull request #569 from wymeditor/issue_569

Cover `this` up