GYP/Ninja Windows build: codegen done, WinXP done, Release done.

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).

.gitignore

@@ -1,6 +1,8 @@
 /out/
+/Debug/
+/Release/
+/Deploy/
 /Telegram/build/target
-/Telegram/build/msvs/
 /Telegram/GeneratedFiles/
 /Telegram/SourceFiles/art/grid.png
 /Telegram/SourceFiles/art/grid_125x.png
@@ -15,7 +17,7 @@
 /Telegram/Resources/art/sprite_125x.png
 /Telegram/Resources/art/sprite_150x.png
 /Telegram/*.user
-*.vcxproj.user
+*.vcxproj*
 *.suo
 *.sdf
 *.opensdf