Unshelved this merge from Stephan and then completed the merge with additional fixes and testing.
Hand fixed some WorldExp compile issues due to changes to OnPaint() signature.
#Integration
[CL 2245992 by Daniel Broder in Main branch]
Removed StartSession/RecordEvent that took multiple params (should use the array overloads instead), fixedup usage
[CL 2228325 by Andrew Brown in Main branch]
In addition, if the AppVersion string is user-specified (either by INI config or command line), it will have {VERSION} replaced by GEngineVersion to allow versioning to be present as well, even when custom AppVersions are used.
#codereview:ian.thomas
[CL 2053796 by Wes Hunt in Main branch]