Bugfix SUP-2266
Fixed whitespaces at the start or end of an inline editable not being properly handled when deleting text.
Bugfix SUP-2184
When Drag & Drop was disabled, blocks with duplicate IDs inside nested editables
would sometimes get the class ui-state-disabled preventing any interaction
with them.
Note that blocks with duplicate IDs are not supported in Aloha-Editor since this
implies invalid HTML markup. This fix is just intended to prevent certain subsequent
errors when duplicate blocks are already present.