Create settings tab

[Gerco Dries]

SMM has accumulated some defaults over time that not everyone agrees with. A settings tab should be created to allow people to change these defaults.

Global settings

1. Auto refresh interval (or disable)
2. File extension mapping to message types(?)
3. Synchronization of broker combo boxes
4. Default tab after connecting to domain
5. Mailing list settings

Per broker settings

1. Default broker per sonic management connection
2. Alternative URL for brokers behind NAT

[Gerco Dries]

There is now a settings tab that contains the autoload profile, topic buffer size and autorefresh timer.