* 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

Card search will now order the following way:

1. Exact match at top
2. Exact match with preceding values sorted lexically.
3. Match contained in word sorted lexically

the original layout is actually more space efficient if using CardFrame
instead of CardInfoWidget and reducing the size of the deck editor
toolbar.

this commit also removes the old search feature by removing the search
button and the clear search button. the clear search menu item is left
in place, however it now clears the filtertree.

finally, the stretch factor for the right frame in the main layout was
reduced to zero so that the card database gets priority for extra space.
this makes more sense because the deck editor does not actually need
very much horizontal space.

renamed filter list modules to filter tree to more accurately reflect
the nature of the data structure.

enable/disable check boxes still not functional

improved token dialog w/ storage inside the deck list - now we need a reliable online source for token data (preferably with pictures)