Small update (v0.2)

I modified the mission success calculation system to take into account the heroes sent and the items taken.

I also decided that only 5 items can be taken per quest.

With the new calculation system, I need to recreate the list of quests, which will take some time.

I added a logger to track important game events (even if it's not very detailed yet); just add --debug when launching in a terminal.

What remains to be done (priority):

1. Add a summary window before starting the quest, showing total costs and income (with OK/cancel buttons).
2. Add more logs to better track game execution.
3. Create a quest report window, showing results and rewards.
4. Balance the quests (the MOST difficult part)—I feel they are too easy right now.