Add a class codec on client side to manipulate codec-related data.
Add a screen that displays on call the number called and the codec used.

note: the screen doesn't display when a call is made with the keypad. TODO

The combo box displays the default or the selected codec

The user can select a codec among the supported one's in the audio settings tab of the config window.
The call is made with only this codec.

TODO: use the other supported codecs to place a call, if the selected one doesn't work

If an registered account is set by default, a call is placed with this account.
If no account is set by default, the call is made with the first registered account of the list
If a non-registered account is set as default, no call is placed and a message popup is thrown.

Also, set up the dialog correctly on opening of an existing account.

Working DBus