add EC frame/slice copy.
overwriteactivesps
Merge pull request #709 from huili2/ec_mb_check

add EC frame/slice copy.
rename some varialbes
  add usagetype parameter in encoder unit test to test screen content
turn off TestHorizontalSearch_SSE41 unit test becasue of random issues
Merge pull request #713 from licaiguo/overwriteactivesps

overwriteactivesps
Merge pull request #712 from ruil2/enc_rename_1

rename some varialbes
Merge pull request #714 from ruil2/enc_setting

  add usagetype parameter in encoder unit test to test screen content