* Add LibraryUpdateRanker
This class provides various functions to generate Comparators that can
be used to order the manga to update.
One such ordering is by relevance:
It prioritises manga that were updated more recently.
Another Ordering is by lexicographic order:
This is the default behaviour.
* Use relevanceRanking scheme
Instead of default(noRanking/lex ranking) now mangaList is sorted with
relevanceRanking.
* Add UI and associated variables & strings for Update Ranking.
* Use user preferences to determine update ranking scheme.
* Refactor relevanceRanking to latestFirstranking.
This name seems to better reflect the ranking scheme and frees up the
name relevanceRanking for future use.
* Set latestFirst scheme as default.
(Changing over from lexicographic scheme)
* Fix 1
[Convert LibraryUpdateRanker to a object.](./files/82f263749f0ae775385b23dd919f1865360db969#r287513539)
[Nitpick: Add lines](./files/82f263749f0ae775385b23dd919f1865360db969#r287540256)
[Replace Java comparator](./files/82f263749f0ae775385b23dd919f1865360db969#r287539976)
[Nitpick: Add local variable](./files/82f263749f0ae775385b23dd919f1865360db969#r287514805)
* Fix 2
[Weird import](./files/82f263749f0ae775385b23dd919f1865360db969#r287513709)
[Default value](./files/82f263749f0ae775385b23dd919f1865360db969#r287540064)
[Use existing Strings](./files/82f263749f0ae775385b23dd919f1865360db969#r287514476)
[Use Library update order](./files/82f263749f0ae775385b23dd919f1865360db969#r287540204)
Viewing a manga's info page for the first time forces a chapter sync.
Prior behavior would cause new chapters to be retrieved for that manga, but with manga.last_update remaining at 0 (until a library update occurred in which chapters were changed).
The new behavior updates last_update any time the chapters are changed via syncChaptersWithSource().
