The `clippy.swf` Flash program is no longer needed and can be deleted.
The configuration property is now incorrectly named, but we keep the
name and update the documentation. Maybe it could be completely deleted
one day, when the clipboard.js solution is known to work and be universally
supported.

When a user had a certificate, i.e. an entry in the Gitblit Authority
database, but the user was deleted from the Gitblit database, then the
Authority application crashes upon loading. This patch prevents the
crash. The deleted user is no longer shown in the Authority. But the
database entry still is kept. This should be improved to show deleted
users and give the possibility to delete them from the Authority's
database.

This fixes #1359

Update Guice to 5.1.0. This version is compatible with Java 17.
The gitblit patch of the servlet extension was ported to Guice 5.1.0,
too.
The update of Guice requires an update of the Guava version, too.
Thus Guava is updated to 27.0.1-jar.

This closes #1390

Add that issue 879 was fixed in release 1.8.0

Also: release notes.

This property allows the administrator to hide the user related part of
the top panel. This can come handy if there's no use for it (i.e. if
Gitblit runs as Gerrit plugin).