v0.3beta

I've added a few more modifiable variables. The defaults for the new variables are basically a clone of h265ize's anime preset.

New Functionality:

1. Reference Frames
2. B-frames
3. Weighted Prediction for B-frames
4. Adaptive B-frame Placement
5. rc-lookahead
6. sc_threshold
7. Strength of Psychovisual Optimization