Added recipe for ankle holster

Half the cost of a holster or sheath and requires survival rather than
cutting or pistol. This seemed sensible as it's a small utility
holster that can hold either a small knife or a small pistol
Made BELTED foot items not count as shoes

This means you can wear an ankle holster at the same time as footwear,
as otherwise BELTED wouldn't do anything on a foot slot.

It also means that now if you're running around wearing nothing on
your feet but socks and an ankle holster you get the "no shoes"
movement penalty.
Fixes ethanol burner crash
On hack fail, only shutdown computers next to player
Merge branch 'ethanol_burner_fix' of https://github.com/reverieAlice/Cataclysm-DDA into merge
Merge branch 'bootstrapping-bootstraps' of https://github.com/rluddy/Cataclysm-DDA into merge
Merge branch 'fix-computer-shutdown' of https://github.com/vidarsk/Cataclysm-DDA into merge