hdf5_ep

Merge pull request #1522 in HDFFV/hdf5 from ~VCHOI/my_hdf5_fork:develop to develop

* commit '7f5741825db0737db5ac46c43009681508a73002':
  Add release notes information.
  Modification based on feedback from pull request.
  Modification based on feedback from pull request.
  There is performance issue when closing an object.  The slow down is due to the search of the "tag_list" to find out the "corked" status of an object. The fix: (1)  Add a counter "num_objs_corked" in the cache structure to track the number of "corked" objects. (2) Skip the search of "tag_list" if the counter is zero i.e. no "corked" objects.

Conflicts:
	release_docs/RELEASE.txt