Update p5-RPC-XML to 0.76.

Changes from previous:
        - fixed typo
        - clean up test suite
        - improved date parsing
        - fix MANIFEST
        - improved arguments-checking in send_request.
- fixes from Devel::Cover analysis.
        - fixes for file-based method loading/reloading.
        - documentation clean-up and update.

(hiramatsu)