Plotting improvements

[maij]

I am just making a list of basic improvements for our plotting routines that would help tremendously.

Pulse sequence plotting

When we plot pulse sequences we could add a 'schematic' alternative similar to what Serwan cooked up in his thesis.
This would make intra-group communications far more effective when people can see what pulses we are applying.

I made a variant like this:

MatPlot handling of 2D data that isn't meshed.

Sometimes we want to plot 2D data where the x-axis/y-axis isn't continguously spaced. This causes the squares to all be misshapen, I think we can easily come up with an alternative.