FAL: Image Processing doesn't respect GFX "thumbnails_png" option
The Task Interface of the File Abstraction Layer defines the
target file extension for graphcal tasks. Previously this was done
with the option "thumbnails_png" from the TYPO3_CONF_VARS.
However, checking for that parameter is not done anymore within
FAL / AbtractGraphicalTask. Thus, all .gif images are shown as .png
files, even though TYPO3 is not configured like that.
This can be seen when using GM, thumbnails_png=0, and creating
a preview image of an animated GIF. The preview will not be shown
The patch introduces the existing option back in to 6.x / FAL.