Cleanups:

 - fix documentation of Net's unique solution option (should have
   tested before last checkin)
 - make unique solutions optional in Rectangles too (same reasons)
 - tidy up various issues in parameter encoding in both games.

git-svn-id: svn://svn.tartarus.org/sgt/puzzles@5818 cda61777-01e9-0310-a592-d414129be87e