Fixes some of the parameters for 1-pass non-cbr mode.
Also includes some cleanups, inlcuding refactoring of the
recode_loop options.

Results on derfraw300 improve by about 5-6%, so that the one-pass
mode is now 13% below the 2-pass mode in speed 0.

Change-Id: I844cc2638694c7574f3be00d41d60b23dc1016f0