lavf/swfdec: remove 8-bit audio FIXME.

Implemented since 624fb5f9.
lavf/microdvd: fix muxing.

This was broken since 1f265f52.
fate/subtitles: add MicroDVD remux test.
vf_idet: Fix macro arguments sideeffect

Fixes valgrind errors
should improve detection scores

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
vf_idet: adapt default scores due to bugfix

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>