Pain-check

This fixes #7781 by interrupting activities/sleep when you take pain.
Might go better in creature.cpp's mod_pain; I'm not sure if NPCs handle
that yet.
Formula

This ought to cover what we discussed.
No Skating on the Broken Legs

As reported on the forums:
http://smf.cataclysmdda.com/index.php?topic=7248.0

If you're knocked down or are short a leg/two, no skating speed bonus
for you!
Add check for default ammo being a valid item type.
Only show melee message when target is visible.

Also: translate the message.
Move the translation before calling str_to_illiterate_str

Translating it in str_to_illiterate_str prevents extractions of the plain string to the translation template.
Also, don't apply it to the *format* string used as first argument to string_format, that's dangerous as the resulting gibberish might invoke unexpected formatting (and refer to more arguments than there are given).

Note that str_to_illiterate_str adds -5...+5 to each character of the string. A space can therefor become a control character, or a '%'.
Assorted fixes to make messages translated

Spelling fix: insesitive -> insensitive

Removed reference to non-existing keymap.txt
Translate messages in mattack::brandish
Merge remote-tracking branches 'dda/pr/8292' and 'dda/pr/8309' into dda-master

* dda/pr/8292:
  Formula
  Pain-check

* dda/pr/8309:
  No Skating on the Broken Legs
Formatting.