phobos commit, revision 1807


user: rsinfu

msg:
[devel] Moved UTF handling to std.utf.

- std.utf: Revived decodeFront & decodeBack because there can be non-string range that generates UTF code units.  Added support for wchars/dchars.
- nativechar: Made UTF8Decoder to simply use decodeFront for decoding UTF-8 input.

http://www.dsource.org/projects/phobos/changeset/1807