Week 12 - Crew Assignments

Added quite a few features this week. 

Crew assignments - you can now swap out which teams your Crew Members are on. (See gif)
Injury effects - Crew members who receive injuries will move slower based on severity
Mission progress - the game will now remember in what state you left a planet last
Trade mission delays - there is now a week long delay before you can trade with a particular planet again.
General cleanup - touched up a few of the missions for additional flavor text and bug fixes.