implements new function 'invalidPath' (Trac 5684)
Fix LHM #10391: various improvements to sortableListing and uses of it

- environment: use share name as additional sort column
- sortableListing: Add support for setting additional sort columns
- sortableListing: Sort by all additional columns, left-to-right
- sortableListing: cast sortColumn to int when setting from HTTP request
- Fix sort in reference lists
- Fix sorting of user's system trust list
Merge remote-tracking branch 'lhm/2.7-lhm' into 2.7-lhm