polyself changes (trunk only)

While making the change to prevent random mail daemons, I noticed
that controlled self-polymorph into a critter specified by class (a post-
3.4.3 feature) rather than by name wasn't excluding NOPOLY monsters so I
checked to see if they were being handled correctly.  Accepting NOPOLY
monsters as candidates was intentional but it had a problem (although
many NOPOLY monsters are NOGEN and vice versa, so the problem wouldn't
show up often).  If I specified A and Archon was randonly chosen, I'd
be told "you can't polymorph into that" but if I retried A and it chose
couatl, the polymorph succeeded.  This changes the way the first case
gets handled:  it skips the message and makes another pick from the
specified class, although that consumes the same retry counter as
reprompting so you might still end up with "you can't" if random picks
come out unfavorably too many times (or if you've typed in some bad
choices first and the counter has already been reduced).

     When doing that, I changed the "you can't" message to say what it
is you can't polymorph into, instead of just "that".

     And I've changed controlled polymorph to accept ESC when prompted
for monster type.  When used, either don't polymorph (for wizard mode
#polyself command) or revert to uncontrolled poly (for all other causes
of polyself) instead of just asking again.  Specifying "*" or "random"
will also produce uncontrolled polymorph.

doc/fixes35.0

@@ -447,6 +447,8 @@ OPTIONS=playmode:normal|explore|debug to choose mode without command-line
 score bonus for ascending is reduced or denied for changing alignment
 player can give a monster class when asked for type of monster to poly into
 likewise when asked about type for #monpolycontrol
+both controlled self-polymorph and #monpolycontrol accept ESC, "*" or "random"
+	when asking for type of monster; ESC aborts #polyself command
 scroll of taming/spell of charm monster now gives some feedback
 doppelgangers can take on the shape of alternate roles' quest guardians
 pile_limit option to control when to switch to "there are objects here"