Fix [#34545] Render layer name is unwantedly translated in composite node editor

Some enums' items actually are generated from data (like the render layers of compo nodes), so they should not be translated. Added a PROP_ENUM_NO_TRANSLATE new RNA flag to tag those enums (only found those for nodes, but may be more of them around).

Also fix similar issue in main list of render layers (Py UI code! :P ).

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@56300 954f8c5b-7b00-dc11-b283-0030488c597c