copy_cnt_8, AVX2 asm code as per new interface, performance improved from 5.13x to 7.59x on HASWELL-I5
asm: avx2 assembly code for dct16
asm: enable copy_cnt8
cleanup header dependencies; dpb should not need encoder.h
search: store rd costs in first pass through intra modes

no behavior change, this is prep work for further refactors
search: don't pass top-level encoder to initSearch()

removes three Encoder members that were only used to communicate data to
initSearch()
analysis: nit
dpb: does not need to include frameencoder.h
search: remove x prefixes from ME helper functions
analysis: minor comment and code cleanups, no behavior change
api: add analysis data structures and param options
api: introduce methods to allocate and free analysis buffers
store analysis information in buffers
cli: add cli options analysis-mode and analysis-file

analysis-mode: save|1 - Dump analysis buffers into file, load|2 - read analysis buffers from the file
analysis-file: Specify file name used for either dumping or reading analysis data