Changes:
* Added kinematic property to Mini_missile and activated collisionDetection.
* Tagged Enemy Shot prefab
* Tagged Player Missile prefab and added rigibody with kinematic property.
* Corrects Life string comparison
* Comment debug logging on player ship shooting
Observations: the use of kinematic rigibodies disables the physics engine, so it doesn't use too much processing.
Disabling the rigibody causes the collision to stop working. Even using the "onTriggerEvent", it seems that Unity needs at least one ridibody to calculate the trigger.