HEVC deblocking filter

Intra deblocking, with correct boundary strengths should also work with inter
No adaptive QP support yet
No support for slices, tiles or WPP
I_PCM support is incomplete, correct no_p and no_q values should be passed to filter function
Preliminary support for bit depths > 8, but not tested
Stores all needed boundary strengths for whole picture.
hevc: rename conformance window structure
hevc: add VUI, HRD and SubLayerHRD data types
hevc: use window_t in VUI and SPS
hevc: parse VUI from SPS
hevc: fix indending on hevc_ps.c
hevc: support NAL 40 (SEI suffix)
hevc: rename window_t to HEVCWindow to preserve namespace rules
Merge stseppo's deblocking filter
Merge kodabb's work on VUI/HRD/SEI support