The notification spec handles -1 and 0 as special values:
-1 -> representation for "undef"
0 -> infinitely
values above 0 represent the timeout in ms.
The notification messages should disappear again and with 0, this insn't
the case. Setting it to -1 lets the notification manager decide the
timeout and displays the notification like all others.
* Working D-Bus desktop notifications
* Remove return type on constructor
* Fix the Windows placeholder class
* Fix wrong variable name
* Fix windows and macOS versions of notificationsmanager
