Debian packaging of Impressive (former keyjnote)

Packaging migrated from svn-buildpackage way without storing upstream, so
debian/* tags are pointing to the commits without upstream sources.
debian-release where merged manually with upstream branch regenerated from
orig.tar.gz files. Since rebranding to impressive, there should be only 2
active branches: upstream/release (+pristine-tar of cause), and tags should be proper (only upstream and debian)