Previous implementation did not consider the amount per card included in the pool already - so the filtered pool always got 1 amount for each card passing the filter.
This should be no problem considering where this method is used. However, to make it portable to other cases, I made the implementation to report the same amount of cards in the new filtered pool.
When StatTypeFilter is used withing Deck Editor (with all PaperCard instance in ItemPool), avoiding checking instance class improves performance a bit (saving a couple of hundreds of milliseconds).
However, when this filter with also other inventory items (pack or deck), the same code as before is executed.
This commit FIXES a bug in card catalog which did not allow to switch the view (on hover) on cards with backface that have more than one instance!
The implementation has been simplified, also removing an unused attr!
The corresponding related Preference in settings has been also simplified to two values (being the other not even used anywhere in the game).
Therefore, now in game settings it will be possible to choose between "NEVER" switch card states, and "SWITCH on HOVER".
The default value in Constant has been updated accordingly!
These new methods will be used to cache the values of Image keys, as well as to determine whether a card has an alternate image (and so key).
Methods on CardImageKeys have been distinguished in names to not confuse them with similar names (but completely different use and output) from InventoryItems interface.
CardImageKeys for PaperCard are also cached in private attribute to reduce OPS in Card Catalogs that are consistently the same.
As for Tokens, the output of these two new methods is the same as getImageKey.
These methods have been also moved to interface (and so class) as this would result in better encapsulation (esp. hasBackFace - using CardRules within the card - similar to `Card` class).
ImageUtil.getImageKey calls will be replaced with these methods, limiting their use only to downloaders (when set attribute can be added or not). PaperCard will always add the set info).
Pattern.quote has some corner cases on MAC not working (`ME/` ended up in three splits).
Resorted back to `//` as the key will never be a true file path anyway!
