NLA: Update context menu to include meta strip operators

The meta strip operator is available in the Add menu, but not in the
context menu.

This patch adds these two operators to the context menu:
* nla.meta_add
* nla.meta_remove

Reviewed By: sybren, RiggingDojo

Differential Revision: https://developer.blender.org/D16353

release/scripts/startup/bl_ui/space_nla.py

@@ -310,6 +310,11 @@ class NLA_MT_context_menu(Menu):
 
         layout.separator()
 
+        layout.operator("nla.meta_add")
+        layout.operator("nla.meta_remove")
+
+        layout.separator()
+
         layout.operator("nla.swap")
 
         layout.separator()