notes:

* keeping with a view/logic separation, although this is quite different to 
  the hexagon game. the main advantages:
	- just a divide and conquer strategy for staying sane 
	- able to debug the logic without the view, or vice versa
	- the logic can be ticked at a lower frequency - or even different 
	  parts at different rates, whereas the view needs ticking every frame

* need to try to keep all the intensive 'every thing vs every thing' checking 
  in the logic side, where it can be done over many frames (i'm thinking the
  lags involved with things like nutrients getting absorbed may not matter 
  too much in this game)

* using a message passing system to formalise the passing of information on 
  the logic side. this makes it possible to have objects sending messages
  at any point, and have them automatically collected up and dispatched to 
  the view

* these messages are also converted to xmpp messages and sent out over the 
  network

* line segments are computed in the logic side, and can be represented any
  way by the view - maybe the players plant will be geometry and everyone
  elses will be ribbons (stoopid LOD)

* in the same way, the line segments can be created in any way by the logic 
  side - eg. lsystem, or different methods per plant (or per twig even)