Changes with Aloha.Editor 0.24.20

Bugfix RT13396

Blocks that are inserted inside of table cells will appear with a delete
button in the same way as when inserted elsewhere in an editable.

Bugfix RT57823

It is now possible to insert tables into editables that are contained in (not editable) tables themselves.
Nesting editable tables into editable tables still does not work. The table plugin will show the insert button,
but will prevent nesting with a message to the user.

Bugfix RT57629

IE default drag and drop behavior is stopped when dragging and dropping block elements.

In some cases the default IE drag and drop behavior was not stopped for block elements,
which end up with pasted elements that could not be removed. The root of
the problem was a Javascript Error (rangy-core) when dragging the element. This error
was thrown due to a bug in the IE selection. With this fix the IE default drag and drop
behavior is stopped and the Javascript Error is catch so the execution of the program
can continue.