scala/scala — pull request #2938 by Ichoran (2013-09-12 00:59:32+00:00)
Title: SI-7725 - Vector concatenation is unreasonably slow

Rewrote ++ to use append or prepend when adding small collections to the end
or beginning of vectors. This solves the extra-O(n) problem for addition of
single elements reported in SI_7725.