Maps cells as tiles layer

Now you can define map cells with a block layer. It's much faster and easier to populate maps by clicking and dragging, and it's expandable to different resolutions without changing the code.

Bug fixes in the context menus for nearby units and available weapons based on their range.

For the next versions, I'll be re-implementing the battle animation system. I'm still not satisfied with the ease of importing animations. I'll focus more on calling up effects and importing animations in the GBA Fire Emblem format this time.