barborder patch: add ability to set horizontal and vertical border sizes seperate from window borders

[tonijarjour]

Hello, it would be nice to have the option to set the size of the status bar border separately from the window borders. Preferably with the setting split into horizontal and vertical borders.

[bakkeby]

I see that there isn't any option to configure this separately.

https://github.com/bakkeby/dwm-flexipatch/blob/b93a5de5587432f21a850c2e86f8478433c30c8e/dwm.c#L1664

Easy enough to expose the above in config.h if need be.

Generally I find that it looks bad when the border size differs from the clients, but can be fun to play around with.

The drawing of the border is handled by X so it isn't possible to differentiate between horizontal and vertical borders, it will be the same size on all edges.