* Separated TOTALINVISIBLE from DONTDRAW as a new flag, so that DONTDRAW
  strictly means the object doesn't generate a vissprite.
* Added ability to customize the aiming shift that other monsters
  experience when trying to target monsters that are shadow, ghost, etc.
  with "aimshift" field in EDF thingtypes. Gave EEPSXSpectre and
  EENightmareSpectre the field.

Subversion-branch: /trunk
Subversion-revision: 2868