Merge branch 'hotfix/3.1.1'
Log the error message if an SQL dump import fails
Get the correct key if a list view field has a foreign key relation
Add a little padding for the install tool license's view

Signed-off-by: xchs <github@gmx.net>
Do not offer to install extensions which are older than the installed version
Add .svgz support to the default `.htaccess` file (see #5938)
Do not copy the autologin hash when duplicating members (see #5945)
Set the correct field type for `tl_files.path` in the DB updater (see #5953)
Fix the "indexPage" hook (see #5967)
Call `sendFileToBrowser()` statically in the download elements (see #5987)
Add some missing office file extensions to the configuration (see #6021)
Do not cache the result of `Model::count*()` (see #5973)
Fix the alignment of the versions menu in IE (see #5962)
Store integers bigger than `PHP_INT_MAX` as string (see #5939)
Decode IDNA domains in any system mail (see #5932)
Correctly validate the options in `Widget::isValidOption()` (see #5951)
Hide the cache message in the repository manager (see #5966)
Replace all insert tags when exporting a page as PDF (see #5990)
Make the GD image max width and height parameters mandatory (see #5940)
Correctly catch the `Swift_RfcComplianceException` in the newsletter class (see #5992)