Deprecate fast quant and strict_quant code.
Small effect on quality as fast was used in first pass but the
effect is basically neutral across the derf set.
The rationale here is to reduce the number of code paths for
now to make experimentation easier. Optimized and fast code
options can be re-introduced later along with other encode
speed options.
Change-Id: Ia30c5daf3dbc52e72c83b277a1d281e3c934cdad
c88d335f7d