First of all, I have performed initial refactoring of 'drink' and 'fill'
commands, including modularizing the code and factoring some of it to the lib.
Also some changes were made to outworld. What this means in practice is that
drinking and filling containers should now work much more uniformly.

Also issues related to swamp water, salt water, etc. should now work "as
expected", instead of .. well, in some unexpected manner.

However, due to how the liquids and whatnots are implemented, this does not
mean that all "drinkable" things are created equal (e.g. potions, alcohol
beverages), but rather, for now, the updates only concern generic liquid
containers such as jugs, barrels, etc.

If you notice some bugs or weirdness, report to me directly.

--
Ggr