Fixed issue with orientation. The ImmutableVector3 implimentation was
not behaving as expected. Returned to a mutable Vector3 for the X,Y,Z
axis vectors and warned developers to not modify. This is a tradeoff of
safety for speed and since no one should ever mess with those vectors,
this has been deemed acceptable by myself and @ToxicBakery.

Signed-off-by: Jared Woolston <jwoolston@tenkiv.com>