Encapsulate and generalize plotting routines.

All plotting routines are now contained in visualize.py and
visualutil.py (instead of plot*.py).
Can now visualize evolution of parameter PDFs

Involved encapsulating and generalizing plotPDF.

NOTE: no routines in this branch have been tested or debugged yet.
Debugged visualize.py and visualutil.py

Had to update setuputil.py and uvmcmcfit.py in the process.  Minor
changes to these two.

Visualize.py has been tested successfully on ADFS07.
Additional bug fixes for uvmcmcfit

Implementation of loadParams was incorrect in uvmcmcfit.
Removed plot*py files.

plot*py files are deprecated in favor of visualize.py and visualutil.py.