Add "autoconnect" option

[tkem]

• Store WS-URL (and name?) of last server in user settings.
• At startup, automatically connect to last server.
• If connection fails, show current server selection.
• If connection succeeds, show notification (toast?), e.g. "Connected to...".
• Make this configurable in "Look and feel" settings, since devs may prefer current behavior.

[tkem]

Additionally investigate startup time; though splash screen should be hidden when first server is detected, this still seems to take too long.

[tkem]

This has become more relevant with introduction of the MusicControls plugin, especially when the app is killed by the system and a click on the notification icon/cover restarts the app.
So it would be preferable to always try to connect to the last server at startup, with a (configurable?) timeout.