app-office/impressive: bump to version 0.11.2 and EAPI 6

app-office/impressive: bump to version 0.11.2 and EAPI 6

app-text/mupdf is now a hard dependency because according to the
upstream maintainer, viewing PDF files will simply not work without it.
It has also taken over most of the jobs previously handled by
app-text/pdftk, which is now an optional enhancement rather than
a dependency - it is masked in recent profiles all it is used for when
mupdf is present is extraction of PDF page titles.

Closes: https://bugs.gentoo.org/579078
Suggested-by: Martin Fiedler <martin.fiedler@gmx.net>
Package-Manager: Portage-2.3.13, Repoman-2.3.3