A class for generating an icosahedron geometry.
		radius — Default is 1. 
		detail — Default is 0.  Setting this to a value greater than 0 adds more vertices making it no longer an icosahedron.  When detail is greater than 1, it's effectively a sphere.
		
See the base [page:PolyhedronBufferGeometry] class for common properties.
An object with a property for each of the constructor parameters. Any modification after instantiation does not change the geometry.
See the base [page:PolyhedronBufferGeometry] class for common methods.