DEMOS: the most trivial exp added
NF: tried to alow to stop a process from GUI

Don't work yet
BF: minor fixes to ticks in plots
BF: very minor work on Zoccolan model

Still doesn't work
Also added a small usage demo
RF: default response keys are now 'f' and 'j'
NF: mouse clicks and SVG export (+tests & demos)

BF: ThickLineStim can now accept default units for lineWidth
NF: exit if pandas or psychopy are missing

also added svgwrite as a dependency
version 0.5.1