Couple updates to overmap system thing

Added proc to imitate movement of stars. Changes icon state and throws all unanchored items in space.

Added var denoting which direction is fore of the ship.
Adjusting speed now applies movement effect on ship's zlevel.

Added working engines system. Only defined type currently is thermal engine.
Acceleration is now based on total thrust and ship's mass.
Added engine control console.

Changed shuttle control console to use custom interface to pick destinations.
Shuttles can now go between any types of sectors, not just ship->sector.
Shuttles cannot return to base if they are too far on overmap.

Moved helm computer to NanoUI.
Helm computer now stores navigation data records instead of polling info from actual overmap objects every time.
Metaobjects now can define if sector is well known, in which case it will be automatically added to helm computer records on creation.
Can add and delete records.

Some pics.
Engine setup: http://i.gyazo.com/f56944e15b8091cdbf31126860139d96.png
Helm interface: http://i.gyazo.com/1de56059c8c3bfd79576f1a42991d678.png