Refs #410. Began work on strcutured headings polyfill for IE7.
Refs #409. Moved plugin documentation to its own top level section and added documentation for the structured headings plugin.
Refs #410. Merged #409.
Refs #410. Wrote stand-alone function in javascript for numbering headings in IE7.
Refs #410. Got the numbered headings to work properly in the editor.
Merge pull request #409 from FriedRice/issue_409

Fixes #409 Create plugin for automatically-numbered headers in IE8
Refs #410. Fixed some variable issues in the structured headings plugin and added the stylesheet for IE7 compatibility.
Refs #410. Added test for the IE7 numbered headings polyfill.
Refs #410. Undo changes made to basic.html test template for plugin testing.
Refs #410. Fixed spelling error in comment.
Refs #410. Consistency fix.
Refs #410. Updated the docs with information on using the plugin with IE7. Also made some small changes so the plugin works properly stand-alone.
Refs #410. Undo changes made to the basic.html test file.
Refs #410. Reorganized files to allow easier implementation of the plugin. Updated docs on how to implement.
Refs #410. Fixed some naming and constant issues. Made the jquery.wymeditor.structured_headings.js file work for both the editor and the stand-alone case instead of having two separate files.
Refs #410. Reimplemented how start nodes work.
Refs 410. Updated documentation.
Refs #410. Made polyfill recalculated headings on keyup instead of keydown and added short-circuiting based on key code. Also added handler to recalculated heading numbering on click event in the containers panel.
Refs #410. Fixed some more naming issues.
Refs #410. Improved constant usage in tests.