TTP# 337136 - SETTINGS: Target Platform settings polish
TTP# 337652 - EDITOR: Limit Project supported Android icons down to 1
TTP# 337650 - EDITOR: There is only 1 icon for Apple for Project Supported Platforms
DesktopPlatform now contains a static array of FPlatformInfo. This can be used to query UE4 about its available platforms, even when they're not available as a target platform.
FPlatformInfo contains the information required by the editor (such as a localized display name and icon), as well as whether a platform is a variation ("flavor") of another, and if so, whether the flavor affects the build output (eg, Win32 or Win64), or the cook output (eg, Android_XYZ). This lets the editor build up nested menus for the "Package Project" and "Cook Project" options, rather than just showing everything as a flat list.
ReviewedBy Thomas.Sarkanen, Max.Preussner
[CL 2095796 by Jamie Dale in Main branch]
Add Runtime/Engine/Private as and Engine private include path
Rename Engine/Private/Materials/MaterialInstance.h to MaterialInstanceSupport.h because it was causing ambiguities
Move cpp files from Classes and Public into Private
#codereview steve.robb, Robert.Manuszewski, nick.penwarden
[CL 2078806 by James Golding in Main branch]
