AR-quiver approach to affine canonical basis elements

This is the continuation of [Y. Li, Affine quivers of type and canonical bases, math.QA/0501175]. We describe the affine canonical basis elements in the case when the affine quiver has arbitrary orientation. This generalizes the description in [G. Lusztig, Affine quivers and canonical bases, Publ. Math. Inst. Hautes Études Sci. 76 (1992) 111–163].