Add x2go compatibility and allow simple auto configuration

[tobydox]

When using fakeXrandr in an x2go session (X-Server-based Remote Desktop) a few changes are neccessary. An x2go server does not provide EDID data for its output and the output screen size is dynamic (remote desktop client window can be resized freely). This patchset implements x2go compatibility and allows a simple auto configuration when using 0 for width, height and/or split position in the configuration.

With these patches, we're able to split the screen vertically while the split position is updated every time we resize the remote desktop client window. Maximized windows inside the x2go sessions are resized automatically.

[phillipberndt]

I noticed that the GUI has issues with such configurations, https://github.com/phillipberndt/fakexrandr/tree/manage-autoconf should fix them.