Fixed ignored sortBy & sortDir snippet params

I had the problem, that the generated sitemap was not nicely sorted as parent, parent/subsite1.html, parent/subsite2.html but accordingly to the menuindex in general (so each resource with a menuindex of 0 in the respective parent showed up after each other, not sorted by menuindex for that parent) I then tried to specify &sortBy=`parent,menuindex` but the params were not taken over into the config for pdoFetch but still had the default value of menuindex...I digged a bit and found they were not there in the merged config array because they (sortby/sortdir) were not present in the $scriptProperties array. Now when I specify &sortBy=`parent,menuindex` it works properly