Node Space: Small feature for Venomgfx, Shift + F select node of the same type

This is a small request from Venomgfx, select a node
and then press Shift + F to select all the nodes of the
same type (of the active node).

The key binding can be change, we thing in a "Find Next" (that is
way the FKEY) with venomgfx, but no problem with change that.

Also I add the entry in the select menu.

release/scripts/ui/space_node.py

@@ -108,6 +108,7 @@ class NODE_MT_select(bpy.types.Menu):
         layout.operator("node.select_all")
         layout.operator("node.select_linked_from")
         layout.operator("node.select_linked_to")
+        layout.operator("node.select_same_type")
 
 
 class NODE_MT_node(bpy.types.Menu):