Too Many Asteroids! (Optimisation Update)

I've finally been able to get to cutting down some wasted frame times to do with asteroids! Previously, an entry level gaming computer would get about 5-10fps when playing with 5000+ asteroids in a small area. Now you can expect between 100-200fps in that same area.

Changes:

-Asteroids now only update every half second or so

-Asteroids now slow down if they're going too fast every update

-Harvesters now mine far more effectively, and don't panic with too many asteroids. (This could still be optimized more)

-An already mined asteroid now spawns mined asteroids when split! (It's now possible to mine the universe dry)

Go even further beyond, pilots!