New meta in LDConfig for default category icon in editors

[Willy Tschager]

Some suggestions based on what is there now:

1. "allow editor" -> "allow an editor"
   
2. "For editor" -> "For an editor"
   
3. "or less) of the category" -> "or less) description of the category"
   
4. "9 digit rotation" -> "9 element rotation"
   

Note: a digit is a single character 0-9, so the rotation matrix cannot be 9 digit. I'm not sure "element" is the best word here, but think that it works well.

I added the above corrections. Roland's remarks are technical and therefore your sandbox.

w.