Feature Request: Support XRandR 1.3 transformation matrix (e.g. scaling)

[tachylatus]

Case:

• Docked laptop in the middle with a 14 inch 1920x1080 display (eDP1).
• Two 24 inch 1920x1200 monitors on each side (DP1-1 and DP1-2).
• Since the laptop screen is too far away to be readable with the global DPI setting, I use xrandr's "--scale" option to apply a transformation to the output, making the effective resolution smaller than the physical display mode resolution.

Proposal/TODO:

• Change current_cfg_xrandr to parse verbose xrandr query.
• Detect and parse transformation matrix, write "transform none" to config if "filter: " is followed by empty string or "none".
• It should not be necessary to modify load_cfg_xrandr.

Caveats:

• Simple output positioning ("--left-of", "--right-of" etc.) is not handled well in xrandr when transformation is in use. This should not be a problem with autorandr since we use absolute "--pos XxY", but it makes the initial setup harder for the user.

[phillipberndt]

I have been using this in the Python version for some time now & it seems to work as expected. So I'll close this. See #12 if you want to implement this for the bash version as well!