subplots in drawmatrix_channels

[arokem]

The ability to draw many matrices side by side in the same figure would be useful

[Xunius]

Do you think adding an optional ax=None kwarg to drawmatrix_channels() would work? If provided, for instance, from a ax = figure.add_subplot(nrows, ncols, idx), subplots could be achieved, and it opens the flexibility to people how they would like to arrange the subplots.

There is already a fig=None optional kwarg. Maybe we could make ax=None take priority if both ax and fig are given?

[arokem]

Another option is to deprecate the fig kwarg (throwing an informative error or warning when that is provided) and to add an ax_or_fig kwarg that does the right thing depending on what kind of object it got. WDYT?