hdf5

* Added missing H5VL package init/term/trace code to H5.c
  and H5private.h.
* HD and other cleanup in H5.c.
* Added dummy VOL class and getter to h5test code.
* Yanked H5I_REFERENCE ID smoke check from test_misc19().
  If you run ./testhdf5 -o misc this test failed due to no
  previous H5R code that would init the package.
* Added H5I_VOL ID incr/decr checks to test_misc19() in tmisc.c.