Move plotting to distinct module; add spiffy FramePlot

Still in the ssp namespace.  The plot.py module also has a FramePlot
class that allows spectrograms to be combined with individual frame
views via mouse clicks.
Merge branch 'master' of https://github.com/bioidiap/ssp

i.e., Import Laurent's mods for PyPI
Correct the previous merge & update setup.py

plot.py needed moving.