Creates the damage component.
Implements the Damage system.
Adds damage component and damage system to the demo.
Adds damage handling to JetState for maneuvering.
Implements a damage state which correctly handles adding damage to the target jet.
Implements jets exploading. This needs to be reviewed though.
Create new entities instead of reusing old ones.
Fixes a UI bug.
Adds hp bars for selected jet and target jet.
Merges master.