Colorized log files

IPython renders traceback messages using ANSI colors. These are
rendered by the ansi2html package if it is installed.
Added new plotview functions

Designed to make it easier to add lines, rectangles, and circles to a
plot. Also, removed redundant setting of log box checks to False. They
are already set in the NXPlotView plot function.
Improved plot window generation

Before, a new NXPlotView could be created with the identical label to a
previous one. Now, the previous one will be automatically deleted. I’ve
also ensured that matplotlib figure numbers fill in missing values,
e.g., a new NXPlotView will have number 2, if 2 had been deleted and 3
already exists.
Added a new parameter_grid function

This should simplify the creation of new dialogs that define a set of
parameters. It is not currently used yet, so it has not been properly
tested.
Improved NXfield compatibility with Numpy arrays

Added a number of overloaded functions so that NXfields can be used in
a wider variety of contexts, without invoking the ‘nxdata’ attribute.
Also the ‘nxtitle’ property now has the root name added to ‘nxpath’, if
there is no title specified.