Adjustment to initial q range estimate and kf boost.

Adjustment to initial q range estimate and kf boost.

Adjustment to initial active based on image size.
Add extra breakout case for kf boost loop.
Small adjustment to q delta calculation for key frames.

Net % improvements for all standard tests sets (-ve values) measured
using c-bvr mode.

(Overall PSNR, SSIM, PSNR-HVS)
Low Res:  -0.223	-0.229	-0.107
Mid Res:  -0.175	0.008	-0.180
High Res: -0.131	0.106	-0.206
NFlix 2K:   -0.390	-0.271	-0.489
NFlix 4K:   -1.370	-0.825	-1.590

Change-Id: I06a39de43594e1a99bb0cb281af15cdb8058a8ed