0020172: \ilParticipants::_getMembershipByType: Wrong SQL query when "true" is passed as argument for $a_only_member_role

finalized and integrated buffer scan with fallback to temp file scan if other than clamav or proc_open not allowed/available

fixed validation of mimetype due to a possibly given charset, especialy because the detection itself returns it ^^

(cherry picked from commit 28f5e2ab)

(cherry picked from commit 7be63a73)

fixed fill questions fallback for rnd passes so allready used questions are avoided to be chosen again

(cherry picked from commit 4a151912)

Added latest versions of Czech and Polish language support, thanks to Petr Vobecky and Dariusz Poczekalewicz

(cherry picked from commit 9d07649f)

(cherry picked from commit 0c298805)

(cherry picked from commit d7c6f82b)

Buddy System: Changed translations / Added new check for accepted contact requests / Fixed unit test / Added new unit tests

(cherry picked from commit 37bee93b)

added logging to dataset, fixed bug #19337: [test52] Bei einer importierten Portfoliovorlage fehlt der Style der Ursprungs-Portfoliovorlage