three-math.min.js should be built by default rather than the non-minimified version three-math.js as per pattern already established.

utils/build_all.bat

@@ -4,4 +4,4 @@ python build.py --include canvas --minify --output ../build/three-canvas.min.js
 python build.py --include css3d --minify --output ../build/three-css3d.min.js
 python build.py --include webgl --minify --output ../build/three-webgl.min.js
 python build.py --include extras --externs externs/extras.js --minify --output ../build/three-extras.min.js
-python build.py --include math --output ../build/three-math.js
+python build.py --include math --minify --output ../build/three-math.min.js