Added ability for PreLoadScreenSettingsContainer to load slate brushes in groups. This way not all brushes are loaded at the same time.
#rb none
#tests Windows Editor, iOS client
#ROBOMERGE-SOURCE: CL 6354660 via CL 6354661 via CL 6354936
[CL 6354941 by thomas ross in Main branch]
- Brings over the necessary engine changes for embedding UE4 mobile as a dylib/so in native mobile app
- Various changes for facial animation, screen recording, others
- ARKit and ARCore plugins were removed, as deemed "not ready"
#rb many people
#ROBOMERGE-OWNER: josh.adams
#ROBOMERGE-AUTHOR: josh.adams
#ROBOMERGE-SOURCE: CL 5201138 via CL 5203024
[CL 5226277 by Josh Adams in Main branch]
