Request: Add support for 1,5 action bar lengths

[Artamus]

Currently the Blizzard Art Bar (that I'm quite fond of) supports classic, 1 bar and 2 bar layouts. It seems the default UI has changed and the current default UI setting is having the micro bar and bag bar stacked on the bottom right while there are 1,5 action bars in the art frame, which I wish was supported in Bartender4 as well. I think it could be added as a separate art bar option or replace the classic layout setting.

[Artamus]

By the way, I'm willing to try my hand at adding that support, if you are accepting pull requests