[dev] [dwm][gaplessgrid] Add option to reverse ordering of created windows

[cne...@gmail.com]

Patch places windows in following order (4 is the last created window):
4|3
2|1

Is it possible to reverse the cycle in the opposite order like shown
below or add some options for windows ordering appearance?
So it would be:
1|2
3|4

And if there are three windows:
1|2
------
3

[cne...@gmail.com]