f-iring without ammo

There was a suggestion in the newsgroup that if you use the 'f'
command when your quiver is empty, that whatever missile you supply to the
"what do you want to throw?" prompt be automatically put into the quiver.
This implements that, and separates most of the common code from dothrow()
and dofire() into a separate routine.  A post-3.4.3 change to dothrow() to
require hands for throwing wasn't propagated to dofire().  With the common
routine, they're much less likely to get out of sync like that.

     This is going into the branch as well as the trunk because the hands
checking mismatch was added there too.

doc/fixes34.4

@@ -387,6 +387,8 @@ intelligent pets will use keys to unlock doors
 destroyed drawbridge leaves some iron chains
 give feedback when a nearby monster grows into a stronger form
 familiars are now created without any starting inventory
+using the 'f' command when quiver is empty will fill quiver if player selects
+	a stack of 2 or more items in response to the "what to throw?" prompt
 
 
 Platform- and/or Interface-Specific New Features