Changed node type definitions to use a dynamic list.

This will allow python or plugin defined nodes to work as well.
(And fixes compile issues with MSVC in yesterdays commit for nodes)

Code provided by Nathan L.
Fixes in his code:
- free_nodesystem() was called too late (after guarded alloc was closed)
- free_nodesystem() was freeing nodes that were not malloced even
- free_nodesystem was using free, not freeN :)
- the typedefs needed to be malloced yes, to allow duplicate nodes like
  group but also for dynamic nodes.

source/blender/nodes/intern/CMP_nodes/CMP_lummaMatte.c

@@ -104,6 +104,7 @@ static void node_composit_init_luma_matte(bNode *node)
 };
 
 bNodeType cmp_node_luma_matte={
+	/* *next,*prev */	NULL, NULL,
 	/* type code   */       CMP_NODE_LUMA_MATTE,
 	/* name        */       "Luminance Key",
 	/* width+range */       200, 80, 250,