settings changed on the server should be forwarded to the client

[Antoine Martin]

Failure to do so can lead to the client believing that something can be toggled when it cannot. The packets can then trigger (harmless) errors on the server.
ie: ticket:1368#comment:6.

[Antoine Martin]

Mostly done in r17804. More toggles added in r17806.

Issues not dealt with:

• some more settings could now be toggled and forwarded to the client - this will have to do for now
• some settings can be toggled, but we don't stop existing operations (cursors are not reset, webcam forwarding does not stop..), this could be added

To test:

• connect the client, verify that most features in the system tray menu are enabled
• disable a feature on the server and verify that the client's system tray menu reflects that (when disabled, the entry's tooltip often states why it is disabled)

ie:

xpra control :10 toggle-feature bell

As of r17808, for more information on which features can be toggled, see:

xpra control :10 help toggle-feature

[Antoine Martin]

Minor related fixes: r17823

[J. Max Mena]

Connecting a trunk r17966 client against a r17823 beta package 2.3 server, I get the following output from the control command when I try to toggle an already disabled clipboard (started with --clipboard=no to simplify things going on):

server returned error code 127
 error processing control command: feature '%s' is set to None!

The '%s' is probably supposed to print Clipboard, right?

[J. Max Mena]

Of note, other than that string, it does forward notifications properly.

[Antoine Martin]

error processing control command: feature '%s' is set to None!

fixed in r17967, error handling improved in r17968, closing.