Place mouse at center of focused view when changing to a workspace on a
different output, if option is enabled. (This replicates existing i3
option.)
This can be triggered in multiple ways:
A) via `workspace <name>` which changes output
B) via `focus <direction>` which changes output
C) via `focus output <name>` which (obviously) changes output
If e.g. a window has a popup open then that will lock the current focus,
making a workspace switch denied.
So don't move the mouse pointer in such cases.
- replace visibilty mask integers with an enum
- set output's visibilty mask on creation
- added update_visibility to manually update a containers visibility (e.g. when it moved to an invisible workspace)