Changed Task class to Sim
Added net_iters and net_temp keywords to run_trial so that you can control the network performance.
Changed W coefficients to a numpy array so we can do fancy things with it later.
Starting out writing some tests, nothing much here yet.
Removed HIT and ERROR
First commit
Changed a whole bunch, let's just say this is the newest version and it seems to work.

I know, deal with it.
Mostly adding comments.  Changed plot_state for the better.