1) Use a functional default (1) for P1.
2) Respond with an empty P2 parameter if nothing is set.
3) Only respond if there is a single parameter.  If there is more than one,
   it's not a request.

While we're here, clean up the formatting of cterm.txt.
Tabs for indentation, spaces for alignment, don't wrap with 80-column
displays using 8-char tabs (default with more).  The ECMA-048 reference
will always wrap however.