...I got rid of duplication for the lblSet col, while also improving translations.
In particular, the "lblSetEdition" column was translated as the "Mistery column" (for some reason :D), whereas a second lblSet2 was instead defined and used, namely "the label tooltip for the Set Columndef".
On this note, this col was also mistranslated in ES, IT, DE - those are the language I could handle so far.
In fact "Set" was intended (and so translated) as "to set" instead as for "Expansion/Edition".
Corrected accordingly! :)
PaperCard instance now includes a new attribute (i.e. `collectorNumber`) that will be used later on to fill in the "CN" Column in List view (see `ColumnDef.java`).
To allow for minor disruption to existing API, the collectorNumber attribute will be handled in a _Property-like_ fashion via the getter method (i.e. `getCollectorNumber`).
In particular, if collectorNumber is marked as `UNSET` (i.e. `PaperCard.UNSET_COLLECTOR_NUMBER`), the corresponding value will be automatically retrieved from the matched `CardEdition`, and updated for later use.
Nevertheless, Constructors including the new parameter have been also set for future API change.
Moreover, the new attribute has been also considered in methods for object comparison, for a more accurate sorting criterion.
The second new addition to PaperCard API regards FOIL cards (i.e. `getFoiled()`).
This method was originally part of `CardDb` API as described in ISSUE #1848.
With this API change, an internal reference to a `PaperCard` (foil) instance will be used to return the foil version of "itself" for each PaperCard Instance. This will avoid proliferation of PaperCard instances in memory, while keeping all information consistent with the original "unfoiled" card.
NOTE: at the moment, every card can be Foiled, with no restriction whatsoever on the _actual_ existence of original (true) PaperCard.
The IPaperCard interface now includes a method to return the Collector Number of a Card.
Moreover, two new constants have been included for Default Art Index (i.e. 1) and a flag to mark the absence of a Collector Number (i.e. 0).
