Binary STLs that start with "solid" are detected as ASCII

[Floppy]

This is actually correct, binary STLs should not start with solid, but I've come across one that does. THREE.js loads it fine, so it's obviously detecting the format in a different way than I'm doing in Mittsu::STLLoader. I should see if I can do the same thing so that we can load cheeky STLs that break the "standard".