Support for simple repeat-x and repeat-y images about spritemapper

[lericson]

msinia asked in e-mail correspondence:

How long do you think this might take you to implement? I forked the project and I'm considering hacking it together myself, as I'm currently needing it.

It should be relatively easy to implement, would require some massaging of the pipelining surrounding the packer so that it can have several modes -- these "pack vertically" and "pack horizontally" modes could be selectable via spritemapper.packing = horizontal or so. Also for this feature not to fall into obscurity an effort documenting it should probably be made.

I would highly recommend keeping the recursive tree structure currently used, so as to avoid reimplementing too much. Also, it would make very little sense to anneal a solution that is either entirely vertical or horizontal as no improvement can be made whatsoever (there is only one solution.)

[lericson]

In short: go ahead, swing by #yostudios on freenode if you have any further questions.