vchoi_fork

Incorporate additional code changes for the H5DOread_chunk patch from GE Heathcare (HDFFV-9934)
This is the similar set of changes that was checked in to 1.8 branch:
Incorporate the code changes that were missing from the original patch:
(1) Additional tests in hl/test/test_dset_opt.c
(2) Fix in src/H5Dchunk.c for direct access when an entry is in chunk cache but not dirty
Tested on platypus, ostrich, kituo, mayll, osx1010test, moohan, quail, emu.