Refactored CARDSIZE to CARD_SIZE.
Added new constant CARD_ART_SIZE.
Made small tweak to the Card class to automatically resize it's image whenever it's parsing a pickled card.
Removed imported_image_data from the card_editor.
Changed the card editor  to create a temporary file of the resized image whenever it saves so it can retrieve the .png data.
Updated card editor to allow the user to decide where and with what name an exported image will be.