dsputil: Split off H.263 bits into their own H263DSPContext
h263dsp: K&R formatting cosmetics

Also remove array element numbering comments.
metasound: Fix error message argument

Signed-off-by: Diego Biurrun <diego@biurrun.de>
avienc: drop the vfr flag.

AVI does not really support vfr properly, only by padding with null
packets.