make it easier to autostart xpra

[totaam]

Both globally (as root) and for individual users.

Then they can have a session ready for use in their system tray.
(assuming they have a usable system tray on their desktop... so not with gnome shell)

[totaam]

Done. Usage:

xpra autostart enable|disable|status

Can be run as root to enable / disable globally for all users.

This also adds the --opengl=nowarn option so we do run the opengl subprocess probe but we don't show a warning when this fails.

Finally, to make it easier to show the client's menu on desktop environments that lack a functional system tray (ie: gnome-shell), use:

xpra show-menu

(also available: xpra show-about, xpra show-session-info)