Cranial flashlight/doc

• The cranial flashlight is marginally weaker than a fully charged flashlight, with a light radius of about 2 fewer squares around the character. Flashlights appear to use 1 battery per 10 turns, so the cranial flashlight is somewhat more efficient.
• Although the conventional flashlight is more powerful, its better light radius is offset by the potentially higher power reserves of the cranial flashlight, which also takes up no inventory space.
• Players should also consider that Implanted Night Vision gives perfect dark vision for only marginally higher power consumption, and may wish to install something other than cranial flashlight if they are likely to acquire night vision soon.