* 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

@ZeldaZach grammar nazi :) 👍

nice alignment over strict tabbing

- removed some info text since oracle imports all cards now and no longer offers sets selection
- added info about token
- `<br/>` --> `\n`
- capitalized `URL` --> http://www.oxforddictionaries.com/definition/english/URL

Translations have been updated.

Imported unzip methods from OSDaB-Zip project;
Adds a soft dependency on zlib to oracle; if lib if not found, oracle
will continue to compile and work but without zip support.

Should avoid the problem explained in #414

Fixed a bug that caused Oracle to be stuck in an infinite loop if the default path checkbox was checked but failed to write.

If a path to cards.xml is set, Oracle will update that cards.xml.
If Oracle is run before a path to cards.xml is set, if default is checked, cards.xml will be saved on the AppData path. Furthermore, this path will be set as the cards.xml path for both Oracle and Cockatrice.
If Oracle is run before a path to cards.xml is set, if default is NOT checked, cards.xml will be saved at the selected path and this path will be set as the cards.xml path for both Oracle and Cockatrice.
If a path to cards.xml is set, if default is NOT checked, cards.xml will be saved at the selected path but this path will NOT be set as the cards.xml path for either Oracle or Cockatrice. This allows people who already have a cards.xml (which may be customized), to still obtain clean copies of cards.xml through Oracle without overwriting their own

It will be saved only if:
* it’s different than the default (the user used a custom url);
* the download actually worked

By default oracle saves cards.xml to the correct path, where cockatrice
will be able to pick it up;
if oracle is not able to determine the path or the user unchecks the
option, oracle will ask for a save path