AI sprite tweaks.

[Mechoid]

Tweaks:

• AI sprites now all properly use -crash for dead icons, rather than _dead for some of them.
• Direct name references have been changed.
  Xerxes - > Ahasuerus, the title of the king of Persia
  Gygas - > bloodylove, code wise. Already called 'Love' in-game.
  Yes Man - > Eager
  House - > sheltered, Already called 'Doctor' in-game.
• Yes Man sprite changed to blue, rather than yellow. Number of icons made useful by adding slight noise.
• BYOND icon removed from new version of Gentoo. Null.laws stayed because it's a generic code joke regarding a runtime.

Additions

• Bored AI core sprite, based on 'Eager'.

Removal

• Xenomorph sprite is no longer accessible.
• Boxfort sprite is no longer accessible.
  Both sprites still exist in-DMI, however their datums have been commented out.

[Anewbe]

Discussion's been dead for a while and I don't see any real harm in doing this. Merging.