Potions / scrolls / wands system upgrade

Potions, scrolls, and wands will now combine automatically when you acquire
them.

"You combine the feline vitreous humour with your current stock, for a total of 3 uses with 66 power."

Toggle this behavior by saying "autocombine off" and "autocombine on".

Potions, scrolls, and wands now tell you their charges remaining and power
in their description:

"This potion contains 3 draughts. The liquid within averages 94 power."

All combined spell items increase in weight, bulk, and value. Ten combined
wands are equal to ten separate wands in all respects. 

**Loot potions no longer go bad after a certain time.**

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Previous bug fixes also:

Potion and scroll spell items no longer have APPLY_YES, wands now do
have it. This should fix the targeting reticle issue.