Function parseMapFile

parseMapFile(text: string): MwlMapFile
Reads a Wesnoth-shaped .map file: key=value header lines (border_size=1, usage=map, and anything else the file carries), then one comma-separated row of terrain codes per line. The header is split off and kept, and the grid goes through the same parseTerrain an inline [map] terrain= string does, so a cell is base^overlay exactly as it is there and a <side> <code> token still marks that side's start.

A file with no header is a bare grid, and the header keys are not interpreted here: what usage or border_size means to a game is the game's business, the same way this framework leaves [terrain_graphics] rules to content.
Parameters
- text: string
Returns MwlMapFile
Example
```
import { parseMapFile } from '@datamoc/mw_games/mwl';

const map = parseMapFile('border_size=1\nusage=map\n\nGg, Gg, Gg\nGg, Gg^Vh, Gg\n');
map.header.usage; // 'map'
map.width; // 3
map.height; // 2
map.codes; // ['Gg', 'Gg', 'Gg', 'Gg', 'Gg^Vh', 'Gg'] - overlays kept as written
```
- Defined in src/mwl/MapFile.ts:42