Use OpenGL 2.0 shaders for the layer height rendering.

Use OpenGL 2.0 shaders for the print path rendering for performance reasons.

xs/xsp/typemap.xspt

@@ -211,6 +211,8 @@
 %typemap{ModelInstancePtrs*};
 %typemap{Ref<ModelInstancePtrs>}{simple};
 %typemap{Clone<ModelInstancePtrs>}{simple};
+%typemap{GLShader*};
+%typemap{Ref<GLShader>}{simple};
 %typemap{GLVolume*};
 %typemap{Ref<GLVolume>}{simple};
 %typemap{GLVolumeCollection*};