add EC frame/slice copy.
update level_idc setting
update
add usagetype parameter in encoder unit test to test screen content
fix typo
overwriteactivesps
Merge pull request #709 from huili2/ec_mb_check

add EC frame/slice copy.
turn off part of preprocessing
Merge pull request #713 from licaiguo/overwriteactivesps

overwriteactivesps
Merge pull request #712 from ruil2/enc_rename_1

rename some varialbes
some traces
Merge branch 'master' of https://github.com/cisco/openh264 into enc_level
add decide frame type for screen content
update format