Use maps created in tiled

The [tiled map editor](https://www.mapeditor.org/) is a useful tool for creating maps.
It would probably be very useful if this could be used to create maps for asciifarm.
There are 3 approaches how this could be done:
- exporter in tiled
- converter from tiled map format to asciifarm map format
- importing tiled map format in rustiifarm

I think the third approach has my preference.

An alternative would be to create a custom map editor