Add more attributes to some plot classes to simplify things commonly done

[rjleveque]

I added new attributes to ClawPlotFIgure and ClawPlotAxes to simplify doing various things in setplot.py, all of which could be done using kwargs and/or afteraxes commands, but these are things I do so frequently that I think they should be made simpler.

I think it is all backward compatible, it just makes some things easier.

The figure below shows a new version of a plot from the standard chile2010 example, using this modified setplot.py that takes advantage of some of the new attributes: https://github.com/rjleveque/geoclaw/blob/plot_updates/examples/tsunami/chile2010/setplot.py

Note in particular:

• white background
• axes labeled Longitude and Latitude with appropriate fontsize
• the title and tick labels also have the fontsize set more easily
• title has time in hour:minute:second notation
• the colorbar has arrows at top and bottom (extend = 'both') to show that waves may be larger than limits of colorbar

Compare to http://www.clawpack.org/gallery/_static/geoclaw/examples/tsunami/chile2010/_plots/frame0005fig0.html

[rjleveque]

I decided to add fontsize attributes directly to title, title, xlabel, ylabel, xticks, yticks, to require less use of kwargs for this common situation, and updated the chile2010 example to use this, and also to illustrate how xticks locations and rotation can be specified in xticks_kwargs .

[rjleveque]

These seem to be working well.