* 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
