Medibot updates!

Medibots have gained two new settings!

- Virus treatment: Medibots can now be configured to ignore viral
infections, even if their beaker contains the cure. This is to stop them
attempting to contain benign viruses released by a virologist.

- Stationary Mode: Medibots now can be configured to remain in place,
healing only adjacent patients. They will not chase patients or attempt
to patrol.
This is useful for establishing triage and recharging stations during
blob attacks.
*They will still respond to PDA summons or AI waypoints.*
Merge pull request #947 from GunHog/Medibots_for_Saiga

Medibot updates!