So far the backend libraries' include paths were relative within this
repository. This means the header files could not be used at their
installed location.
This change replaces them with "<>" includes to fix that problem and adds
a new include directory so building everything at once still works.
With this change it should be easier to actually split some parts into
another repository if this one would become too big.
The following uses of QCC1/PlasmaComponents2 remain:
```
…/DetailView.qml:import org.kde.plasma.components 2.0 as PlasmaComponents // for Menu and MenuItem
…/DevicesPage.qml:import org.kde.plasma.components 2.0 as PlasmaComponents // for Menu and MenuItem
…/DirectoriesPage.qml:import org.kde.plasma.components 2.0 as PlasmaComponents // for Menu and MenuItem
…/DownloadsPage.qml:import org.kde.plasma.components 2.0 as PlasmaComponents // for Menu and MenuItem
…/FullRepresentation.qml:import org.kde.plasma.components 2.0 as PlasmaComponents // for vertical TabBar
…/RecentChangesPage.qml:import org.kde.plasma.components 2.0 as PlasmaComponents // for Menu and MenuItem
…/TopLevelView.qml:import org.kde.plasma.components 2.0 as PlasmaComponents // for Highlight and DialogStatus.Closed (used with Menu and MenuItem)
```
* Use the name as sorting criteria and fall back to the ID if there's no
name
* Use new SyncthingSortFilterDirectoryModel also for Plasmoid's filtering
* See https://github.com/Martchus/syncthingtray/issues/75
* Support triggering actions via the context menu in the regular tray like
it is already possible in the Plasmoid
* Support copying via the context menu in the Plasmoid like it is already
possible in the regular tray
* Reduce repetition of coding patterns using templates
Specifying the with explicitely on every level seems to fix this. Not sure
whether it is the best solution but Qt 6 will likely mess up everything
anyways so let's not put further effort into the QML stuff at this point.
Apparently just setting HOME does not work anymore. At least in my Plasma
setup XDG_DATA_HOME and XDG_CONFIG_HOME are now interfering. This change
introduced an extra helper script to take care of the environment variables
which unsets the XDG_… variables and also takes care of QT_PLUGIN_PATH by
the way.
* Lazy initialize systemd interface and don't initialize it
at all if the unit name is empty
* Allow to supervise/control system-wide units in addition to
user units (see https://github.com/Martchus/syncthingtray/issues/61)
* Avoid redundant code