hdf5_ep

[svn-r9764] Purpose:
    New feature

Description:
    Add some additional features to the skip list code that was needed to
fully support all the features that the threaded, balanced binary tree code
has.

    Also, updated the property list code to take advantage of a few of the
new features.

Platforms tested:
    FreeBSD 4.10 (sleipnir)
    Too minor to require h5committest