mscolab_server_url is not updated in the msui_settings.json

[ReimarBauer]

once succeesful logged into a mscolab server we have also to store the recent url in the json config msui_settings.json on the var mscolab_server_url

This var is mandatory to become set for the autoplot docking widget

[ReimarBauer]

we have to that also for the autoplot dockingwidget which has an early copy of the configuration.

at all we have to save in self.config_for_gui all config vars which we do add by modify_config_file-