Give changelings different objectives

[Erik]

• Escape on the Shuttle with the idenfity of another crew member whilst wearing his ID.
  
• Escape on the Shuttle in lesser form.
  
• Escape on the Shuttle in horror form.
  
• Identify and eliminate any competing changelings.
  
• Change at least XX% of the crew into RANDOM_CREWMEMBER.
  
• Accumulate at least XX corpses in AREA.
  
• Hijack the emergency shuttle and escape with at least one other changeling.