Moved packages to non-free sections.

Moved packages to non-free sections.
Added watch file.
Added postinst section and debconf templates into ion3 binary package to run uscan and require acknowledgement when installing an outdated version.  Arranged to copy watch file into the binary package, and added necessary dependencies.
Removed dependency of ion3-dev on ion3, since ion3 will not be automatically installable and is not strictly required.  Arranged for ion3-dev to have its own copy of required docs.