Implement version of lowercase that only check a to z, instead of all...

Implement version of lowercase that only check a to z, instead of all characters, and don't rely on functionality provided in the transcoders.


git-svn-id: https://svn.apache.org/repos/asf/xerces/c/trunk@176372 13f79535-47bb-0310-9956-ffa450edef68