[Feature]: Startup on tray

[marinhuz]

Feature Description

Thanks for the project.

If possible, please include the option to launch the program with the system in tray mode.

What version of Celeste are you using?

0.8.3

[parkgott]

That would also be a wish of mine

[hwittenborn]

This is already implement, though I must admit it's quite poorly documented.

If you pass the --background parameter to Celeste while it starts up, it should automatically start in the tray. Making it actually run on startup depends on your desktop environment, though feel free to send a message here (or in the support channels linked in the README.md) if you'd like some assistance on that.