hdf5_ep

[svn-r29292] Maintenance: Restored RELEASE.txt from rev 27551 and added entries from Allen and Binh-Minh.

Other main changes that were done to trunk should be documented before the 1.10.0 code freeze.

This file will be added as HISTORY-1_9_0-1_10_0.txt to the 1_10 branch when the branch is created and will be part
of the HDF5 1.10.* source distribution.