hdf5_chunking_query_bmr

[svn-r17262] Description:
	Bring r17261 from trunk to 1.8 branch:

	Refactoring dataset layout information to segregate the constant items
from the variable items (at least from a storage standpoint).

Tested on:
	FreeBSD/32 6.3 (duty)
	(h5committest performed on trunk)