Changed the love.graphics internal code to always use a default shader when none is set externally, and replaced the deprecated OpenGL vertex attribute code with the equivalent generic vertex attribute functions.

This will simplify the code and make it more maintainable when OpenGL ES 2+ support is added, compared to using the deprecated VA functions on desktop GL and the generic VA functions on GLES.

--HG--
branch : minor

src/modules/graphics/opengl/wrap_Graphics.h

@@ -89,6 +89,7 @@ int w_setCanvas(lua_State *L);
 int w_getCanvas(lua_State *L);
 int w_setShader(lua_State *L);
 int w_getShader(lua_State *L);
+int w_setDefaultShaderCode(lua_State *L);
 int w_getSupported(lua_State *L);
 int w_getCanvasFormats(lua_State *L);
 int w_getCompressedImageFormats(lua_State *L);