put the texture cache into it's own file

src/GPU3D_TexcacheOpenGL.h

@@ -0,0 +1,25 @@
+#ifndef GPU3D_TEXCACHEOPENGL
+#define GPU3D_TEXCACHEOPENGL
+
+#include "GPU3D_Texcache.h"
+#include "OpenGLSupport.h"
+
+namespace GPU3D
+{
+
+template <typename, typename>
+class Texcache;
+
+class TexcacheOpenGLLoader
+{
+public:
+    GLuint GenerateTexture(u32 width, u32 height, u32 layers);
+    void UploadTexture(GLuint handle, u32 width, u32 height, u32 layer, void* data);
+    void DeleteTexture(GLuint handle);
+};
+
+using TexcacheOpenGL = Texcache<TexcacheOpenGLLoader, GLuint>;
+
+}
+
+#endif