hdf5

[svn-r27144] Description:
    Normalize trunk against the metadata_cache_merge branch, in preparation
for merging the branch into the trunk.

Tested on:
    MacOSX/64 10.10.3 (amazon) w/serial & parallel
    Linux/64 2.6.x (koala) w/serial
    Linux/32 2.6.x (jam) w/serial & parallel