Fix WSJT-X QSO panel mode updates

[VA3THP]

WSJT-X sends QLog both the current decode mode and the TX/logging mode in its
Status message. For the New Contact panel, the TX/logging mode is the one that
matters: it is the mode WSJT-X will use for the QSO, and it affects things like
worked-before checks.

This fixes two small issues in that path:

• tx_mode was parsed, but status.tx_mode was accidentally filled with
  mode, so the actual TX mode was lost.
• WSJT-X mode changes were only sent to the New Contact panel when no rig was
  connected. With a rig connected, the panel could keep the rig's data mode
  instead of the WSJT-X QSO mode.

The WSJT-X spot table is unchanged. This only changes the New Contact panel:
it now uses WSJT-X's TX/logging mode for the QSO mode.

[foldynl]

I have no comments on the fix in WsjtxUDPReceiver.cpp. Thanks.

Regarding the change in WsjtxWidget.cpp, I have several comments. The main point is that the intention to change the mode only on a disconnected rig was intentional.

Unfortunately, your fix can cause the rig mode change to compete with the mode information from WSJT-X. That is quite an undesirable side effect.

The second side effect is that your code changes the band filter width every time a status message from WSJT-X is received. This is also unwanted. The rig should be fully controlled by WSJT-X. QLog should not make any decisions in this case.

Or did I miss something?