For FT8 mode:
1. Open LU 13 in the proper way.
2. Disable diagnostic LU 51.
3. Add keyboard shortcuts CTRL+Plus, CTRL-Minus, to adjust audio Tx frequency
in even 50 Hz steps.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7749 ab8295b8-cf94-4d9e-aec4-7959e3be5d79