fix compile warnings
add funtion pointer for search methods
add reference frame managment for screen content [still in progress]
Merge pull request #615 from volvet/clean-warning

fix compile warnings
Merge pull request #619 from ruil2/vp_dpb

add reference frame managment for screen content [still in progress]
Merge pull request #616 from sijchen/fme_merge81

[Encoder ME] add function pointer for search methods
Merge remote-tracking branch 'upstream/master' into travis.osx