Improve Tray facilities

[sghpjuikit]

There seems to be an excellent tray library in town: https://github.com/dorkbox/SystemTray. Reasons for:

• using native menu look & feel seems like a good idea
• hi-dpi icon
• switching to SystemTray should be relatively easy

This is low priority. Far ahead I'm also thinking about some custom and over the top tray menu (like animated radial corner menu).

[sghpjuikit]

I'd like to remove the tray menu and use something more pretty, some corner fade in or sidebar thing.