* moved the mpeg-motion and mpeg-idct options to the mpeg_vdec plugin

* moved the mpeg-motion and mpeg-idct options to the mpeg_vdec plugin
* added a few *_LONGTEXT descriptions to main.c
* on win32 DVD/VCD_DEVICE defaults to to D:

Could anyone finish the *_LONGTEXT descriptions in main.c. There aren't
that many left right now, just the ones I didn't really know what to do
with.
If someone also wants to review and change the already existing
*_LONGTEXT descriptions, he is welcome as well because there are not
really high quality descriptions :(