Merge pull request #303 from yacomink/master

Scope findMatchingSelectionParent to current editor
Added justify* buttons
Merge pull request #307 from JoTrdl/master

Added justify* buttons
Fix #308 by passing clipboard content through self.htmlEntities before inserting
added tests for onerror exploit with disableReturn false and disableReturn true
whitespace fix
Merge pull request #309 from pascalpp/disableReturn_exploit

Fix #308 by passing clipboard content through self.htmlEntities
Check editor element for data-disable-return on return, not the target element of the keyup