Avoid the PHP session handler to generate errors when we try to retrieve a session after the headers being sent to the browser.

Bugfix: if an optional configuration is missing, we shouldn't register it to reuse it later (i.e. loading a config file as optional first and as mandatory later would make the second call to work -while it shouldn't-, since an empty config was loaded during the first call).

Try with "composer update" instead of "composer install". The latter does not support --prefer-lowest.

Since this branch is now officially released we need to support it.

* Remove 404 link to SSP news; this is covered on simplesamlphp.org now.
* Make screenshots link relative, so docs don't trigger insecure
  content warnings.
* Compress png images.

Fix/keep empty folders

Update translations to the latest changes registered in translation.rnd.feide.no. The portal is now down, so any new translations must come as pull requests.

(being respectful with occurences that might change the behaviour, i.e. default database prefixes)

This reverts commit 7a801334.

This reverts commit 09c5a23f.

Otherwise you get 404's when SSP is not in the root of the vhost.

SHA-1 is still supported but needs to be configured explicitly if you need it.