Fixed issue where offsetParent wouldn't always be set.
Added itemDefaults option support to Menu.js.
Refactored FormatControls.js to add the UI components after plugins have been initialized.
Added new importcss plugin. Lets you auto import classes from CSS files similar to the 3.x behavior.
Fixed a few issues with importcss and related changed.
Reworked FormatControls.js to use addButton instead of UI Factory.
Merged in IE11 fixes.
Fixed IE 11 empty editor issue.
Fixed some IE 11 FocusManager.js issues.
Fixed selection restore logic for IE 11.