MAHOUT-1222: Fix total weight in FastProjectionSearch

Sometimes when removing a Vector that's in pendingAdditions, the wrong Vector
gets removed.
This happens because the closest Vector is removed rather than the one that's
equal to it.



git-svn-id: https://svn.apache.org/repos/asf/mahout/trunk@1484697 13f79535-47bb-0310-9956-ffa450edef68