Routine packmsg now tries the shortlist (Type 1 prefix or suffix) first.
Then it tries to to make a valid message using a Type 2 prefix or suffix.
If both fail, it packs the first 13 characters as a free-text message.
The GUI now generates the most useful messages with compound callsigns
of all valid types.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@4533 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
