Make audio/video bit rates "properties" #734
follow #731. This commit
toxav_basic_test is fixed, either.
As for adding legacy functions back, it should be finished in #732.
Review status: 0 of 4 files reviewed at latest revision, 2 unresolved discussions, some commit checks failed.
"audio_bit_rate" is now just "bit_rate".
"video_bit_rate" is now just "bit_rate".
Comments from Reviewable
follow #731. This commit completely removed all things in namespace bit_rate, and deprecated functions are to be added back in another commit. set_xxx() is treadted as a property of namespace audio&video, same as bit_rate change event. toxav_basic_test is fixed, either.