Reorganisation of COLLADA import code. Classes have been split into their own files.

No functional changes.

Where necessary extern "C" {} blocks have been added.

source/blender/collada/DocumentExporter.h

@@ -21,6 +21,10 @@
  *
  * ***** END GPL LICENSE BLOCK *****
  */
+
+#ifndef __DOCUMENTEXPORTER_H__
+#define __DOCUMENTEXPORTER_H__
+
 struct Scene;
 
 class DocumentExporter
@@ -29,3 +33,5 @@ class DocumentExporter
 	void exportCurrentScene(Scene *sce, const char* filename);
 	void exportScenes(const char* filename);
 };
+
+#endif