Editor map rendering

Map rendering is almost completed. The autotiles are not implemented yet, so at the moment they are drawn as normal tiles.

When switching between layers, some tiles are partially hidden in order to highlight those that are drawn on the selected layer. The event layer shows all the tiles and enables a grid.

The map can be displayed at different scales. Scrolling works correctly.

The map size limit is 500×500 tiles, as in RPG Maker. Huge maps do not need a lot of memory. The memory usage remains below 20 MB at the moment.