add function pointer
Merge pull request #591 from sijchen/me_merge91

[Encoder ME] add function pointer initialization
    add preprocessing parameter for screen content
Merge pull request #592 from ruil2/enc_processing

    add preprocessing parameter for screen content
add ExpandPic encoder unit test
Merge pull request #593 from ganyangbbl/encUT_ExpandPic3

add ExpandPic encoder unit test file
Add feature search basic functions
    add scene change detection in workflow for screen content
Merge pull request #596 from ruil2/enc_processing

    add scene change detection in workflow for screen content
Merge pull request #595 from sijchen/fme_merge12

[Encoder ME] Add feature search basic functions
add layer sps/pps to decoder context
Merge pull request #599 from licaiguo/add-sps-pps-for-each-layer

add layer sps/pps to decoder context
add usagetype setting for screen content
fix ios encDemo build
Merge pull request #601 from volvet/fix-ios-build

fix ios encDemo build
Add alternative search methods
fix typo
add scene change for screen content
Merge pull request #600 from ruil2/vp_console

add usagetype setting for screen content
Merge pull request #603 from ruil2/vp_update2

add scene change for screen content

Approved by Sijia.