Refs #429. Added a large amount of tests for the various cases of the issue.
Refs #429. Parser now unwraps content of block elements not allowed in list items when they are found in list items.
Refs #429. Fixed tests so that they all pass in all versions of IE.
Refs #429. Added test for unwrapping content from nested DIV elements within a list item.
Refs #429. Fixed a couple variable issues.
Refs #429. Updated CHANGELOG.
Merge branch 'issue_429' into issue_418

Conflicts:
	src/test/unit/specific_feature_tests/xml_parser.js
	src/wymeditor/parser/xhtml-parser.js
	src/wymeditor/parser/xhtml-sax-listener.js