Correct STDP learning and add a few tests
Rename srm.py to spiking.py
Remove debug print
Add weightplotter, change plot_psth so that one can define neurons to print out
Refactor SRM model and add a new model 'Izhekevich'
Add the izhekevich demonstration

Based on a matplotscript published on:
http://www.izhikevich.org/publications/net.m
Rename spiketrain to spiketools
Add an example model (180 input and 180 output neurons)
Remove some unused imports
Simplify the simulate method
Small correction

add parentheses around print