[LIB] Rotate DMD 90° for portrait setups where screen is not rotated

[DeWim]

I play vpx in FS mode on one monitor, so the playfield and dmd are on the same monitor.
Because of this i need to be able to rotate the dmd to the left, so the 'rol' or 'ror' option for vpinmame.

Is there a way i can do this with the dmdext dmd? I only see an option to flip the image but no option to rotate.