Target validation

[hwilling]

1. user selects a target for an attack or utility action
2. system checks if selected target for attack or utility action is a valid target given the actions rules a. system determines target is valid allows action to proceed b. system denies action from happening

[hwilling]

made progress on this, we need the HUD to work (@l-hurd314) in game so that we can use that as a selector for targets

function in controller is available for checking distance between ships, uses fvectors of each object location