ham/chirp: Update to python3 version of chirp

chirp used to use python 2.7 and py-gtk2.  Upstream has changed to
python3 and wxWidgets.  This commit moves pkgsrc to the new version,
called "chirp-next".  Besides the python version and toolkit change,
installed program names change.

This remains a daily snapshot as upstream does not have releases.  As
always there are bugfixes, minor improvements and support for
additional radios.

