more about sign, CLEARSIGN, *LOCAL-SIGNS*



I've committed ff12e8bb and merged it into branch-5_31. I'm planning
to make another 5.31 release (5.31.1) and so that will be in it.

Hope this helps,

Robert Dodier

PS.
commit ff12e8bbaad95451ff1e3c1452bcfd5c380c7fb2
Author: Robert Dodier <robert_dodier at users.sourceforge.net>
Date:   Wed Sep 11 21:16:23 2013 -0700

    Ensure that 'sign' does not make any changes to assume database.
    
     * src/compar.lisp:
     (1) in $SIGN, revert previous change (commit 3137b946) to call CLEARSIGN,
         which has the unhappy side-effect of killing off stuff introduced
         by asksign (which is supposed to persist)
     (2) in SIGN-MEXPT, cut out calls to functions which push facts onto
         *LOCAL-SIGNS* (namely TDZERO, TDPN, etc)
    
     * tests/rtest_sign.mac, tests/rtest_ask.mac:
       collect tests which require interaction into rtest_ask, and tests
       which do not, into rtest_sign.
    
     * tests/testsuite.lisp:
       remove rtest_ask (interactive tests) from list of test scripts