Conformance fix: set sps_max_dec_pic_buffering to correct value
Modify CU split cost.
Moved intra mode cost calculation to a function

Conflicts:
	src/search.c
Changed intra search to skip some modes speeding it up
Add smarter rough intra search.

- Directional intra mode search is done using halving search from the best
  known mode. Starting modes are vertical, horizontal and the 3 diagonal
  modes.

Conflicts:
	src/search.c
Always check DC and planar intra modes.

- At least one of them is always in predicted modes, but to make sure they
  are both included add them explicitly.
Avoid unnecessary intra dir searching.
Use more starting points for smaller blocks in intra search.
Clean up intra search.
Add option to disable fast intra search.
Merge branch 'intra-search-tweaks'