Enable xrandr outputs one-by-one, --pos 0x0 first

Enabling more than one or two outputs at once may result in this error:
/usr/bin/xrandr: Configure crtc 1 failed
This happens on my Dell Latitude E7440 with three monitors connected.

Disabling many outputs at once still seems safe.

Output positioning may be ignored by xrandr in some cases.
To circumvent this, make sure the output with --pos 0x0 is enabled first.
Enable outputs in pairs of two (Follow-up to commit f4cce4d)