Feature request: Allow transmission to start part-way through a cycle

[tomevans80]

In WSJTX most of my contacts happen by me looking through the list of CQs, taking 3 or 4 seconds to select one, and starting a reply 1 or 2 seconds into the cycle. WSJTX syncs the transmission so it all lines up and the receiver can still easily decode this without any problem.

It would be great if FT8CN could allow this as well, as at present I have to wait another full odd/even cycle to pass before transmission starts.