Health and Stamina Update

Reworked the Health Bar system
- Moved the offset code for health bar from Mob class to HealthBar class
-- Made some small fixes to HealthPack class that this broke
- Moved the initialization of HealthBar from Mob class to individual Mob
classes
-- This will allow more freedom in health bar customization for
individual mob types
Added a stamina system
- Only exists for the player
- Initialized at 100
- Prevents the PC from sprinting indefinitely