Initial work on downloading cards through fallback URLs.
This change will add in the ability to proceed to the next URL
should the first one fail. First trial shows that it's working,
but needs more refinement.
Return a list instead of a single url. This is the start
of getting many possible urls instead of one. Functionally
identical except that the primary url will be attempted for
cards without a muid.
* main.cpp: removed path checking and db loading
* card database: merge card loading methods into a single one
* settings cache: take care of returning safe paths for decks,
replays, etc..
* main window: if db loading fails (eg. first run), propose to run
oracle
NSIS: propose to run cockatrice instead of oracle
Rework card database loading
* Move carddatabase-related method out of deckeditor tab
* Load cards in another thread and render them progressively
* Optimize database reload after enabled sets change
Fix deck editor column width
* removed the noCard hack.
* getCard() no more creates cards instead of just returning existing
ones
* Fix the “edit tokens” dialog.
* PictureLoader: avoid trying to download twice the same card
* PictureLoader: correct return of card background
* AbstractCardItem: avoid recalculating card color at every paint
Use a different file to save custom tokens
Misc required improvements
* Use nullptr;
* Refactor CardInfoWidget to use CardInfoPicture and CardInfoText
instead of duplicating code;
* Added CardInfo::getColorChar()
* Fixed some potential crashes
* removed dead code related to CardInfoWidget
* Don't require a restart after adding a new custom sets file
* Bump CMake requirements to 3.1
