Update RPM packaging

gnome-inform7.spec is also not generated by configure anymore; it should
have its version and release number hardcoded.
Remove Z5 and Z6 compilation

Inform's Standard Rules do not fit into the Z5 and Z6 virtual machines'
memories any longer, so those formats are not supported. Loading an old
Z5 or Z6 project silently converts it to Z8.
Load "disconnected" page if Public Library fails

There is an error page that provides a nice explanatory message if for
whatever reason the Inform app is not able to access the Public Library
page.
Update Debian packaging

Now uses debhelper instead of CDBS. Tests are disabled because they
require an X server to run.