Edge Case Hexen 2 Misdetection

[RandomErrorMessage]

Tools such as bspinfo, vis and light misdetect Quake 1 formats as Hexen 2 if the map lacks texturing. This is borderline user error because it's incorrect workflow, but also I'm new to quake mapping and got confused why I couldn't run vis or light on my map. I don't know if isHexen2() can be improved, or possibly just add a warning in the error message about misdetection.

This is a regression from stable.