How to reliably detect static/animated models?

[Mugen87]

It would be good to know if there is an intended way to detect whether an object is animated or not. Right now, M2Loader counts the number of bones although this approach is not robust.

three-m2loader/M2Loader.js

Lines 394 to 397 in e71c776

	// TODO: Find out a better way for detecting static models
	// Problem: Even static models have some bone definitions
	if ( boneDefinitions.length < 8 ) return null;