Add sparse and dense layers

[joshuajbouw]

One of the big milestones for data optimisation. Now it is possible to have sparse and dense layers as well as layer sprites ordered by Z level!

Changes

Fixed

• Separated non-public API out
• Fixed issue with tiles_to_renderer_parts (now dense_tiles_to_renderer_parts) which pushed ALL the tiles, not just a single layer.

Added

• A lot more documentation
• Added Z layers to the tile map
• Versioned prelude with most likely used methods, traits, structs, enums

API Changed

• MANY public API were sorted and removed from public API
• Z layer added to TileSetter::push method:
• MapResult -> TileMapResult
• MapError -> TileMapError

Before

let mut setter = TileSetter::new();

// Sets a tile at x1, y1, z0.
setter.push(Vec3::new(1.0, 1.0, 0.0);

After

let mut setter = TileSetter::new();

// Sets a tile at x1, y1, z0 and z_layer 0.
setter.push(Vec3::new(1.0, 1.0, 0.0), 0);

• DeprecatedTileMap::new_chunk_with_tiles (Sorry! No longer fits in the scope...)

Closes

#9 #6

[joshuajbouw]

This is fairly feature complete up to this point.

[alec-deason]

Seems good to me. I still have some thoughts on minimizing the API but I want to work with it as is some before I push on that and it's out of scope for this PR anyway.