The command-line utility can query and set the frame rate of IVF files, since
apparently encoders don't care too much about setting proper values in the IVF
header. Also, add the utility to the synthesis build.
On the playback side in EDuke32, get rid of the 1/(2*fps) "correction" if the
FPS numerator is <1000 (presumably used in older encoders) and properly print
the frame rate's fractional part.
git-svn-id: https://svn.eduke32.com/eduke32@3131 1a8010ca-5511-0410-912e-c29ae57300e0
