Refactored the magic bytes into two QLists: one containing a list of QStrings representing the supported extensions, the other containing a list of QByteArrays representing the magic bytes in hex.
Refactored the image loading loop to be two nested for loops: the outer loop iterating through the QList of paths to folders in which to search for images and the inner loop iterating through the QList of supported extensions.

Switched back to using QFile instead of QImage for saving as QImage's save function adds overhead to the file size, leaving me unsure whether the original image is affected.

So [card]jotun grunt[/card] works as well as [card]Jötun Grunt[/card].
Also I removed some debugging information I accidentally left in.

9sec was causing too many timeout issues.

Timeout from both client and server perspective needs to be revisited

 * Use the new, shortest API m=
 * for a card, grab prices for all sets
 * use the lower price for a card from all sets, but avoid prices=0
(e.g.: some M15 cards have no price yet)

Added better support for custom card images by prioritizing a check for card images in <Pictures path>/<CUSTOM> before all other checks.

As suggest by Daenyth in #185

Query card database to get a multiverseis for a card.
Get card price using that id instead of card name.
Tested Aether, split cards, question elemental?, _____

Probably settingscache would have been the correct place for the enum,
but keeping it in the same class/file where price sources are defined
sounds cleaner to me

* the previous PriceUpdater class has become abstract
* BLPPriceUpdater inherits the old code for blacklotusproject.com
* DBPriceUpdater is a new implementation for deckbrew.com
* add a setting to choose between the two