Quick Dark (or Custom) Plot Background

Quickly updates the color of a figure so that it can be easily displayed on a dark background, by changing background color and converting axes, labels, etc to a light shade. However, if backColor and foreColor are passed it can also be used to convert to other custom color schemes. By default (if none are specified in arguments), background is black and foreground is white.

Input Arguments:
- valid handle for the figure to be converted
- RGB vector for desired background color {black if none passed}
- RGB vector for desired foreground color {white if none passed}

This may not be an entriely comprehensive tool, in fact it most certainly is not. It is just my current quick and dirty solution to the fact that the energy barrier to my using pretty dark background (or any custom color) presentations is usually my plots. The default call (only input hFigure) gives somewhat similar results to the command 'colordef black' and this function may in some respects be less comprehensive, but it works better for my own personal needs.