split maps into regions for easier importing

[ScanMountGoat]

Some wismhd files appear to contain more than one named "map". Selecting the map ahead of time will reduce resource usage in applications like Blender.

[ScanMountGoat]

This is based on the map part data. Data chunks have a part id that matches up with the named map part for both xc2 and xcx. https://github.com/atnavon/xc2f/wiki/map-parts#mappartdata