* [xrandr] Fix bug 453, clean up data model
* Fix: 'devices' was originally not a list, just assigned each time it
was parsed. Made that a list and appended to it.
* Removed distinction between unassociated/associated devices
* Added test for @marcin-koziol's problem
* Put tests into separate test methods
* Formatting cleanup
* Backwards compatible type syntax
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Co-authored-by: Kelly Brazil <kellyjonbrazil@gmail.com>
