- Requires -xcconfig on the GenerateProjectFiles commandline
- Resurreceted the old non-xcconfig code in another namespace so that we can have both code paths side-by-side
- Had to change a little bit of XcodeProjectFileGenerator to manage the side-by-side classes
#preflight 62d61dbf164251d065b9388b
[CL 21164425 by Josh Adams in ue5-main branch]