Use standard dbus interface for notifications

[peterhoeg]

Further to #5, would it be possible to use the standard DBus notification interface?

A bit of background. I wrote a small tool to handle reminders in .ics files synced from O365 and needed a mechanism to notify. I thought "no problem, I'll use libdbus as it allows me to also read the do-not-disturb status before actually sending the notification and I can then just send them directly" but I then discovered, that when you simply use the org.freesktop.Notifications interface, the do-not-disturb bit is handled automatically for you.

I understand that you might want to use libnotify to abstract away the details of the various platforms on which you run, but maybe there is a way to have it simply use the dbus interface so the desktop environment will handle it like any other application doing notifications.