MetaLang, codegen_style and codegen_numbers utilities are now
built by GYP targets, rules added for codegen_style and actions
added for codegen_numbers and MetaLang.
WinXP supported without Windows 7.1A SDK, but with explicitly
setting MinimumRequiredVersion=5.01. It works (and that is strange).
If you attempt to use MSBuild instead of Ninja you should add
the latest Windows SDK include paths to include_dirs, because v140_xp
toolset implies the Windows 7.1A SDK (and is ignored by Ninja).
It already builds in Debug, using rules for Qt MOC and RCC.
Need to start use rules for styles/langs/numbers, test on WinXP.
Need to support Release and Deploy configurations.
