Working on UWP support

Support Universal Windows Platform (UWP):
- Windows 10 App
- Windows Phone
- Xbox One

project/vs2015.UWP/raylib.App.UWP/pch.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <memory>
+#include <wrl.h>
+
+// OpenGL ES includes
+#include <GLES2/gl2.h>
+#include <GLES2/gl2ext.h>
+
+// EGL includes
+#include <EGL/egl.h>
+#include <EGL/eglext.h>
+#include <EGL/eglplatform.h>
+
+// ANGLE include for Windows Store
+#include <angle_windowsstore.h>