DOM Performance:

1. add removeNamedItemAt to avoid calling findNamePoint again if index is already know.
2. fix findNamePoint so that binary search can be used in both regular (DOM Level 1) and namespace (DOM Level 2)


git-svn-id: https://svn.apache.org/repos/asf/xerces/c/trunk@173939 13f79535-47bb-0310-9956-ffa450edef68