[developers] moved rmrs/convert.lisp to rmrs/rmrs-convert.lisp

[Ann Copestake]

since we are now under svn and can rename files without messing up
history, I have just moved rmrs/convert.lisp to rmrs/rmrs-convert.lisp
- I have edited lkb.system and mrs.system

I assume this is enough to get round the PET problem for which Francis posted a 
workaround.  I'd be grateful if someone who is using PET and RMRS/DMRS
would test

Ann