Reorganize crate

[aleokdev]

This is an updated version of #43. It splits lib.rs into the following modules:

• animation: For Frame
• error: For ParseTileError & TiledError
• image: For Image
• layers: For LayerTile, Layer, LayerData, ImageLayer & Chunk
• map: For Map & Orientation
• objects: For ObjectGroup, ObjectShape & Object
• properties: For Colour, PropertyValue & Properties
• tile: For Tile
• tileset: For Tileset
• util: Private, for all the macros & internal parse functions

While by itself this change won't improve the external interface by much, this reorganization will allow for further development on current types such as Properties, which is an alias right now, and is essential to allow for quickly browsing through the library.

[mattyhall]

LGTM

[bjorn]

@alexdevteam I've just adjusted bevy_ecs_tilemap to work with the current git version of rs-tiled: bjorn/bevy_ecs_tilemap@eb360e5

I found the need to prefix every rs-tiled type with its specific module name a bit annoying. Is that how things are done in Rust, or is there a way to avoid this?

What I've tried is to add something like use tiled::map::Map; at the top, but that didn't really work since it created an ambiguity with bevy_ecs_tilemap::map::Map. Personally I would still like the basic types to be available at the top level, like tiled::Map, since it allows resolving the ambiguity while avoiding the verbosity of map::Map.

[aleokdev]

Yes, I agree that publically exporting essential types on the root is a good idea. Could add a few pub uses on lib.rs.