Changes double return behaviour to single return.
Fixes a problem with backspace.

In some circumstances, the blocks array is not ordered by position.
Getting the block by array position would result in the wrong block
being picked for joining the text into. In the worst case, the picked
block was the one to be removed, effectively removing text.
Multiple fixes.

There were some issues with cursor positioning, nested divs in Chrome,
non-nested divs in Firefox, as well as obsolete function names.
Updates compiled files.