talking gecko (trunk only)

Suggested by <email deleted>, chatting to a gecko will
give a reference to GEICO's car insurance ads.  I limited it to when
the hero is hallucinating.  Chatting to a gecko monster, or to anything
capable of speaking--except for a couple of previously handled special
cases, like quest leader--which happens to look like a gecko at the time,
or (50:50 chance) to a shopkeeper regardless of appearance, you'll get
"15 minutes can save you 15 zorkmids", parodying "15 minutes can save you
15% or more on car insurance".  (One of my comments says there's a chance
to interfere with shopping, but that's not accurate since using #chat to
get shop price quotes doesn't use the monster-response routine.  I left
that comment in anyway; the "15 minutes" response might interfere afterall
if someone mistakenly thinks they can save gold by waiting that long
before paying their shopping bill.)

     I don't think we ever found a good place to add some reference to
GEICO's other--and more relevant to nethack--slogan, "so easy a caveman
can do it".

doc/fixes35.0

@@ -463,6 +463,7 @@ Sunsword's light radius depends on its curse/bless state
 Add M-C and M-R meta-key shortcuts for #conduct and #ride, respectively 
 can now use ESC to cancel out of prompts for playing musical instruments
 being crowned gives an additional benefit:  one extra skill slot/credit
+chatting to a gecko or shopkeeper while hallucinating gives alternate message
 
 
 Platform- and/or Interface-Specific New Features