Moving rfkill to the main event loop had unexpected side-effects.
Notably, the network module mutex can block all the main thread events
for several seconds while the network worker thread is sleeping.
Instead of waiting for the mutex let's hope that the worker thread
succeeds and schedule timer thread wakeup just in case.
Open rfkill device only once per module.
Remove rfkill threads and use `Glib::signal_io` as a more efficient way
to poll the rfkill device.
Handle runtime errors from rfkill and stop polling of the device instead
of crashing waybar.
Add additional fields, namely `source_volume` and `source_desc`
Add `tooltip-format`, reverting to default behavior if not specified
Add additional CSS classes, namely `sink-muted` and `source-muted`
Destroy request is not specified for foreign toplevel manager and it
does not prevent the compositor from sending more events.
Libwayland would ignore events to a destroyed objects, but that could
indirectly cause a gap in the sequence of new object ids and trigger
error condition in the library.
With this commit waybar sends a `stop` request to notify the compositor
about the destruction of a toplevel manager. That fixes abnormal
termination of the bar with following errors:
```
(waybar:11791): Gdk-DEBUG: 20:04:19.778: not a valid new object id (4278190088), message toplevel(n)
Gdk-Message: 20:04:19.778: Error reading events from display: Invalid argument
```
This error occurs because of an incorrect assumption that the size of
the list of nodes that contains the focused window is the number of
windows in a workspace.
The windows in a workspace are stored as a tree by Sway, rather than a
list, so the number of windows has to be found by counting the leaves of
a workspace tree.
