Ensure that the screen is redrawn after updating options as it may change some
aspects of the display.
aimake: Improve warnings from aimake, and display of warnings from gcc etc
aimake: Support flex and bison specifically if they're available

The fallback to lex and yacc, complete with their stupid filename
conventions, still exists.
Loosen 'i' command dropping restrictions

This allows a few items that weren't previously allowed to be dropped to be
dropped, in particular a heavy iron ball with which you are punished. I think
this also affects alternate weapons.

For convenience, also added a W_WORN macro which represents an item you are
wearing anywhere on your body (but not one being wielded).
Calculate container weight on special levels.

Now the chest with the wand of wishing, and the chests containing Vlad's
amulets, have the correct weight at all times. Fixes bug C4X-005.
Improve monster !/oI message when telepathic.

Now gives a separate monster when a monster drinks a potion of invisibility or
zaps itself with a wand of make invisible if you cannot see the now-invisible
monster, but you can detect it telepathically. Previously, the message was
confusing because you were told that the monster disappears, but no change
occurred to the glyph.

No message change for monsters detected via skilled/expert monster detection
since the background colour of the monster will change, and the message doesn't
seem that odd.
Auto-identify /oT when zapping yourself.

This uses the same identification logic as vanilla uses for zapping your steed
with /oT. It is somewhat questionable, but at least it's consistent.
Add a return statement to silence a warning.
Fix a misplaced t
Better handle moats with new is_moat function.

Also fixup a trailing space and make more use if is_* for other types of
terrain.
Merge remote-tracking branch 'ais523/nicehack' into nicehack

Conflicts:
	libnethack/src/cmd.c
Add missing return values to do_oname
Merge changes from upstream.