Release v0.4

- Each mage now has "color points" to determine what cards they can play

- Functional shop where you can buy/sell cards and buy upgrades

- Working deckbuilding! Cards in the sideboard can be added to the main deck

-  3 save slots for multiple saved games

- Added a bunch of confirmation dialogs so you don't accidentally do things you didn't mean to do

- A bunch of typo fixes, bug fixes, and UI tweaks