Add alternative search methods
clean multi-threading macro
    use WelsLog instead of fprintf to have a unified trace output
Merge pull request #604 from ruil2/vp_trace

    use WelsLog instead of fprintf to have a unified trace output
Merge pull request #602 from sijchen/fme_merge22

[Encoder ME] Add alternative search methods
fix bug of assign data
Merge pull request #606 from huili2/PredUT_fix

fix bug of assign data of UT code
Add EncoderMB UT test file, and reformat UT files.
Merge pull request #607 from ganyangbbl/encUT_EncoderMB2

Add EncoderMB UT test file, and reformat encoder UT files.
Merge pull request #605 from volvet/clean_mt_macro

clean multi-threading macro
    use function pointer in reference frame management
Merge pull request #608 from ruil2/vp_dpb

    use function pointer in reference frame management
[Encoder ME] add memory allocation basics for FME
Merge pull request #609 from sijchen/fme_merge32

[Encoder ME] add memory allocation basics for FME
Merge remote-tracking branch 'upstream/master' into travis.osx