Refactoring event attributes.

[HexDecimal]

Events are a mess right now and need to be cleaned up. Multiple bad ideas need to be deprecated and removed in a way which allows for backwards compatibility.

• [x] Fix case in window event types as they do not match the type hints.
• [x] Rename mouse pixel attributes to just position and motion in preparation to removing their tile attributes.
• [x] Context.convert_event should return a new event with updated positions instead of editing events in place.
• [ ] A new function needs to be added to convert coordinates when contexts are not available.
• [x] Deprecate tile attributes in mouse events.