* Added better handling for sortByList manual placements
If manual placement specifications show up in an inconvenient order,
sortByList, will go to the trouble of processing them in that order.
* Added tests to confirm solution to (#3296)
...That custom tag ordering will not choke when tiddlers get sorted after their dependencies have been placed around them
* Corrected list-after bug when referencing external titles
* Using more error-proof $tw.utils.hop in sortByList
* minor indentation correction in test-tags.js