ENH: Modify plot API to allow plotting of only data points - closes gh-36 (#43)
ENH: Modify plot API to allow plotting of only data points - closes gh-36 (#43)

Rename dataplot -> eqdataplot, which is just a wrapper around the new
dataplot.

Dataplot now only plots *data* for comps, phases, conditions. eqdataplot
used to do this, but starting from a Dataset from equilibrium. Now
eqdataplot constructs comps, phases, conditions from Dataset objects.

dataplot now takes a plot_kwargs argument that can be used to control
the maplotlib arguments from the higher level APIs. While doing this,
the default scatter marker size was changed from 100 to 50.
PhasesResearchLab/ESPEI