Selective plotting

[cdhinrichs]

When plotting, sometimes I just want one plot, say rand_esd2 or log_log or whatever. Currently the plot argument is boolean, and if True, then it generates all plots. This behavior can be preserved, and also generalized as follows:
In constants.py declare a set of constants, one for each type of plot. If plot=True then replace with plot = WW_ALL_PLOTS. If plot=False then replace with plot=[]. If plot=[WW_PLOT_RAND_ESD] then only do that plot.
The change would be,

• declare the constants
• handle the default boolean cases like above
• change all of the if plot conditions to if WW_PLOT_XXX in plot as necessary

This way, I can use the tool in a notebook and have it only show the rand_ESD2 plots, rather than generating everything and having to load from disk just to show the one that I want.

[cdhinrichs]

Note to self: Check this before submitting PR:

        deltaEs:  bool, default: False
            Compute and plot the deltas of the eigenvalues; only works if plot=True. 
            Plots both as a sequence of deltaEs and a histogram (level statistics

--- Found it. It's fixed.