bug fix: presentations finally accessible

Due to an error in the configuration of the site, the previously announced presentations were not accessible. This error has been fixed, and a number of additional presentations have been added. We still are missing some presentations at the workshop or the minisymposium. If this is the case for yours, please send it to info [dotcenaero] hiocfd4cenaero [dotcenaero] be or koen [dotcenaero] hillewaertcenaero [dotcenaero] be.