[!!!][TASK] Remove ExtCore and ExtJS Adapters

Remove the standalone slim "ExtCore" functionality and
the custom adapters for prototype 1.5, jquery 1.1 and YUI
completely from the core (only use ext-base adapter natively).

Drop all configuration to activate ExtCore in FE.
Drop all configuration to configure custom adapters
when loading ExtJS.

Resolves: #68001
Releases: master
Change-Id: I254b37f3637e829d7528422c13b41a8e96d90cd1
Reviewed-on: http://review.typo3.org/41028


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>