CommConfigurationWindow - don't try to manually center, now that it is a proper QDialog
CommConfigurationWindow - changing the link type should update the window
Comm Settings - move the "link type" combobox to the top, and clean it up

* The "Simulation" option is now not selectable.
* If the link is a simulation, then you can't change it to a different link type.
* The OPAL option is not shown if support is not compiled in.
* Fix the buddy, tab order and accelerators in the GUI.