Added MPL license headers
SectorRenderer renders entities in sector, manages particle systems for ship thrusters
Thrusters apply torque based on orientation and position relative to ship center of mass
GameManager controls the player ship's thrusters
Player can dock with station if they are near
Context menus now support dropdown options
Context menus can now be created for UI elements with new dedicated cancellation click catcher
Game manager creates context menus based on the object being clicked, no need for duplicate code in every context that object appears
