Add paranoid:swim to prevent typoing into water or lava

In the name of accessibility: Prevent moving into dangerous liquids.

Now with themed rooms, water and lava are more common, and it's
unreasonable to expect blind players to check every step for those.
With paranoid:swim, just prevent normal walking into those liquids,
unless you prefix the movement with 'm', or if the liquid would not
harm you.

Doesn't completely prevent an accidental dunking - for example
if the hero is impaired or couldn't see the liquid.

This comes from xNetHack by copperwater <aosdict@gmail.com>
with some changes to the code.

doc/fixes3-7-0.txt

@@ -1410,6 +1410,7 @@ reading a blessed scroll of light has a chance to improve bless/curse state
 	of wielded Sunsword or worn gold dragon scales/mail similar to dipping
 	those into holy water; cursed scroll has chance to worsen the state
 added a chronicle of major events, and optional live logging of those
+paranoid:swim to prevent accidental dunking into dangerous liquids
 
 
 Platform- and/or Interface-Specific New Features