* Every C++ project now has an "invalid" configuration. Trying to build any solution configuration which does not apply to the project will now build that, which prints an error rather than building a completely different configuration.
* Available configurations are now parsed from C# files, so the "Release" configuration will now be used if "Development" is not available, and platforms are supported correctly.
* Programs are now built in game and editor configurations.
#rb none
#jira UE-59288
#ROBOMERGE-SOURCE: CL 4432766 in //UE4/Release-4.21/...
#ROBOMERGE-BOT: RELEASE (Release-4.21 -> Release-Staging-4.21)
[CL 4432767 by ben marsh in Staging-4.21 branch]
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