Need way to handle Tiled format versions #6
Description
I was under the impression that the major versions of Tiled would keep a compatible map format, but this assumption is very much incorrect.
Of particular pain: the current JSON parser can't read object properties for Tiled 1.2
Reading from JSON tilesets is also likely a little broken because of how they're stored now.
In general we should have a way to handle different versions. That means writing down which version(s) cl-tiled is able to handle, and at the very least shooting an error if a user attempts to load a newer version, allowing them to continue if they so choose.
For reference, cl-tiled was originally written to support 1.0.0 maps.