Further refine presets
Further refine presets

The rd-complexity of slow presets is better with a less agressive GOP.

Adding the GOP as part of the preset improved BDRate enough, that it
didn't make sense anymore to have a veryslow target the best BDRate.
Instead, push that responsibility to placebo by making it a little bit
faster.

ultravideo/kvazaar,ultravideo/kvazaar,ultravideo/kvazaar,ultravideo/kvazaar,ultravideo/kvazaar