fix caret tests
fix caret after <br>
add tests for shift + enter
Don't leave emptied contains when creating lists
Don't recreate lists inside of lists unnecessarily
Merge pull request #1205 from cprerovsky/hm-ui-refactoring

howling mad ui refactoring
Streamline ui code
Merge remote-tracking branch 'arseny/howling-mad' into howling-mad
Post merge clean up
Use Dom.isListContainer()
re-implemented button state toggling based on parent nodes of current caret position
updating the block format pulldown still open