* Removed remaining picture handling from card database and cardinfo
 * removed the “noCard object” hack

Move the “check unknown sets” method inside the cards database, so that
it can be executed when the card database gets reloaded after a card
database update.
Additionally, show the user a welcome message the first time they run a
new cockatrice version, so that they know why they get shown the “edit
sets” window and how to hide/disable sets.

 * card: cache simpleName for each card
 * deck editor: remove double comparation of searched term with card
name when sorting

Drop CardInfo’s own pixmap caches; use QPixmapCache instead.
Use QPixmap references instead of pointers.
Being stored in QPixmapCache, all card images are now subjected to
QPixmapCache’s size limit

Let oracle add a basic TK set in cards.xml
Unify all the code previously using the string literal “TK”

and save them in cards.xml

Should fix #412

Removed the QLists for determining image format. Instead, using QImageReader, both when downloading/saving and when loading, to determine the correct format (Cockatrice now supports all QImageReader-supported formats).
Image loading still uses one for loop to iterate through the QList of paths to folders in which to search for images.

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.

Ref #122

Better error message and allow the user to still connect

Ref: #102

Add HQ card option

* add multiverse id to cards.xml
* remove pictures urls from cards.xml
TBD:
* fix/clean oracle’s gui
* add support in cockatrice