hdf5_ep

[svn-r16515] To improve the performance of querrying the info of a link(bug #1404).  When the index was set to
creation order in querry function but there's no creation order indexed in the file, the library tried 
to build and sort a table of all links.  To optimize it, let the library use the B-tree for names of 
links.

Tested with h5committest.