Fixed tabindices on single file page
Simplified tag filter
Moved tag filtering logic from Library to its own filter
Implemented filtering of only untagged files to files page
Fixed: Opening only filtered untagged files from files page
Added option to filter only tagged files on files page
Removed untagged file page because untagged files can now be seen in files page
Fixed: when unchecking both untagged and tagged filters, all files are shown