Make rustproof/erodeproof/fixed known by default

All cases of rustproofing in the game are known, so having the rknown
bit off by default only meant cluttering item menus during ID with
entries which had everything known about them except this one thing.

This also causes rustproofing to be known when reciting a scroll of
enchant weapon/armor while blind and confused, since the result is
unambiguous.
Dipping pure and diluted potions of the same type combines them

A stack of pure potions dipping into a stack of diluted potions of the
same type will now create a single stack of diluted potions.  This also
accounts for the blessings and curses of both stacks.

This reduces the backtracking created by water trips to and from potion
stashes leading up to and during alchemy sessions.
Remove the alchemy tax

In NetHack, dipping 2 potions into 1 potion gives 2 new potions instead
of 3, so an alchemy dip always cost 1 potion, encouraging mass potion
stashing for one big efficient alchemy session.  This change removes
that cost and its resulting incentive.

This only works with UnNetHack's alchemy system; NetHack's rules could
contain "alchemy loops" that would allow interchangable potion sets.
Identify reflecting dragon armor when they reflect

Reflecting dragon scales and scale mail will be formally-ID'd when worn
by the hero or a monster and it gives a message that it reflected
something.  This is consistent with the amulet of reflection.
NH4: Allow entering the quest before turn 2000

Capped alignment is always enough now, even if it's less than 20.

Allow entering the quest before turn 2000
Alex Smith <ais523@bham.ac.uk>
4dbd209f9cec1f03545a0f8cd350fc2f12c01b0b