U162 - killing shopkeeper with unpaid thrown objects

While an object is being thrown, it isn't on any list.  This means that
killing a shopkeeper with an unpaid object wouldn't be able to clear the
unpaid bit.  By the time the object lands, the shopkeeper is gone, and then
it's too late.  Added a new global to track a thrown object, set it and later
clear it in throwit(), also clear it as needed in dealloc_obj(), and check
it in setpaid().  It should be possible to use this global to avoid losing
thrown objects during hangup saves as well.  But that can wait.

doc/fixes34.1

@@ -383,6 +383,8 @@ avoid buffer overflow from long or too many -s params
 wake up first if trying to crawl out of water while asleep
 while waiting, don't try to change into were form when already in were form
 steed should remember traps encountered while mounted
+killing shopkeeper by throwing unpaid things would result in
+	"item not on bill" impossible error
 
 
 Platform- and/or Interface-Specific Fixes