Move math and some file and data conversion files out from native to Common.

Buildfixing

Move some file util files

Buildfix

Move KeyMap.cpp/h to Core where they belong better.

libretro buildfix attempt

Move ini_file

More buildfixes

ext/native/ui/ui_screen.cpp

@@ -5,7 +5,7 @@
 #include "base/display.h"
 #include "Common/Input/InputState.h"
 #include "Common/Input/KeyCodes.h"
-#include "math/curves.h"
+#include "Common/Math/curves.h"
 #include "ui/ui_screen.h"
 #include "ui/ui_context.h"
 #include "ui/screen.h"