[bugfix,documentation] Fix copy'n'paste bug in a comment
Directly implement the correct values for overlapSize and ghostSize

Rather than having the GridView ask the Grid for them.
[bugfix,documentation] Fix missing word in a comment
[cleanup] Replace tabs by spaces
[cleanup] Remove obsolete comment
UG version 3.11.0 is mandatory now
[cleanup] Remove test for UG version 3.9.1-patch10

That test existed to enable additional features if a new-enough version of UG
was available.  Since we now require the newer 3.11.0 anyway, the test has
become obsolete.
[cleanup] Remove hacks around bugs in pre-3.11.0 versions of UG

More specifically, for the issues described in FlySpray 170

https://dune-project.org/flyspray/index.php?do=details&task_id=170

and FlySpray 810

https://dune-project.org/flyspray/index.php?do=details&task_id=810

The underlying cause for the first issue was fixed in UG 3.10.0
in UG commit dc15886dde4d25d8502f2b85e00e74e7537672d0

The underlying cause for the second issue was fixed in UG 3.11.0
in UG commit 7c656a8c22987163a7669fe66713cb513f652047