[BUGFIX] Implement EXT: usage in addModulePath

Make it possible to use EXT: for resolving paths in addModulePath

Resolves: #68361
Releases: master
Change-Id: I6e79a3e11c42530fadaa25e4dc64f05e6d6a0e32
Reviewed-on: http://review.typo3.org/41695


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Susanne Moog <typo3@susannemoog.de>
Tested-by: Susanne Moog <typo3@susannemoog.de>