Isolated to a single Primitive2D class based on the AnimatedSwitch-
Primitive2D which does the specializing in one place. Buffers small
GIFs completely, handles 1st frame always buffered, huge GIFs get
animated by just playing he next frame.
To reach more with the current approach we would have to re-implement
AnimatedGIF import, replay it internally on a sys-specific Surface
and blit the current content (with alpha) to our display

Change-Id: I46c3325fa7936df73bea9a9284a0421f1475a34b
Reviewed-on: https://gerrit.libreoffice.org/26103Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>