Weekly drop #13: UI cleanup, mostly

Hi there,

apart from a host of bug fixes, I mostly straightened out some of the UI this week.

• No pop-ups stacking up, and less intrusive, non-blocking notifications.
• Clearer indication in the card game view, if you have the right tools available at all, or need to wield a different tool.

And I completed the "end-of-turn event" mechanics! More events and effects will be added over time, but the system seems to work well now (see screenshots).