first iteration of theora_control() support. Apps now can provide their own

th_quant_info data or ask the encoder to switch to VP3 profile (that's currently
the default anyway).

Cleaned up some underscore-prefixed variable names that were inherited from theora-exp

Got rid of PROFILE_FULL and PROFILE_VP3 - those weren't exposed in the API. Now apps
can use theora_control() to get something equivalent to PROFILE_VP3. If the apps want
"PROFILE_FULL" (that was a 6 quant table thingie) they can just provide the necessary
data.

svn path=/trunk/theora/; revision=13256