ENH Forward more arguments to MPL plot routines

[drewejohnson]

A handful of our plot routines don't allow the user to pass on additional arguments to the underlying plot call, making configuration and tweaking a little frustrating. I'll highlight some here in no particular order that I think we should allow. Basically it would boil down to allowing **kwargs in the method signature, and then sending those directly to ax.plot or ax.errorbar, depending on how the plot is drawn.

• sensitivity
  

  serpent-tools/serpentTools/parsers/sensitivity.py

  Lines 408 to 409 in ee88bf4

  	ax.errorbar(energies, yVals, yErrs, label=label,
  	drawstyle='steps-post')

• results
  

  serpent-tools/serpentTools/parsers/results.py

  Lines 852 to 857 in ee88bf4

  	ax.errorbar(xvals, ydata[:, 0], label=label,
  	yerr=ydata[:, 0] * sigma * ydata[:, 1],
  	)
  	else:
  	ax.errorbar(xvals, ydata[:, 0], label=label,
  	)

  
  The last line here should be ax.plot rather than ax.errorbar too
• homog univ
  

  serpent-tools/serpentTools/objects/containers.py

  Lines 454 to 455 in ee88bf4

  	ax.errorbar(xdata, yVals, yerr=yUncs, label=label,
  	drawstyle=drawstyle)