[Evolution] evolution-persist: background notification extension module for Evolution

[Hu Jialun <hujialun comp nus edu sg>]

Hello all,

I have put together an Evolution extension to keep evolution running in 
the background after all windows are closed, since evolution-on has been 
unmaintained for years and is deprecated in various aspects.

The preliminary project can be found at 
https://gitlab.gnome.org/SuibianP/evolution-persist and should be 
straightforward to build and install. An amd64 binary compiled against 
Evolution 3.42.4 is available at https://paste.c-net.org/IndecentOlympus 
for convenience.

Please be informed that this extension is still in its early stages and 
may not be stable enough. That being said, it would be of great 
assistance to test it out and any feedback would be much appreciated, 
preferably through the issue tracker at the abovementioned repository.

Best regards,
Hu Jialun