Fixed issue with tables nesting when inserted inside of a list and added a test for it.
Merge branch 'master' into issue_406
Refs #406. Made table insertion check for the selection of any selectable table element to avoid nesting tables rather than only checking for the selection of a td element.
Refs #406. Added more tests to test for insertion into a th element or a caption element.
Merge pull request #406 from FriedRice/issue_406

Fixes #406 Sometimes inserting a table in a list item that already has a table nests the tables in IE8