Major update

* got rid of the universal ForceRegistry in SimScreen, and now i just
  keep a list of IForceGenerators in Organism.
* Fixed that annoying aspect ratio glitch, by letting EyeCamera take graphics device as constructor arg, so it can respond to viewport changes.
** now things drawn and camera take graphics device so they can respond to resizes
* Broke out new project Forever.SpaceParititions
* Added SignalEncoding, for creating inputs to the nervous system
* Adde Odometer and scroll bar thruster like x3
* IPartition<T> interface
* PartitionRegion/PartitionSphere, these are for keeping an IEnumerable of
  things in a spacial region.  Used for update set, draw set.  Also manages
  an experimental space of hunters, more to come on hunters later
* ControlledCraft manages rigid body for the "player"
* Hunter spawner on action bar D1, not fully implemented. it just goes in a straight line
* Added some models from turbosquid