[!!!][TASK] Drop RTE.userLinks functionality

The option RTE.userLinks has been broken for some
time now and with the upcoming Tabbing API this can
be added again with an extension.

Resolves: #68116
Releases: master
Change-Id: I592923f5c7218001d28f7aff3c2e48c1533b2d48
Reviewed-on: http://review.typo3.org/41185


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>