-QApplication, no QGuiApplication: the later avoids the systray to
display
- Workaround for invisible app icons when vendoring
- Make border visible for snaps

this is an attempt to solve the problem we're having with snaps, in
which Overlays are not correctly displayed.

isEmpty was not enough, have to go to .txt field

we've agreed that the autostart behaviour can be unexpected;
we'll expose the ability under preferences (it can be controlled via cli
right now).

tweak sizes and alignments

thin font was not rendered properly in osx. workarounds no longer
necessary; main.cpp tried a font load that doesn't need to be done in
c++.