hdf5_ep

[svn-r16280] Description:
	Bring revision 16278 back from revise_chunks branch:

	Update layout information in DCPL to unify all information in one
underlying property and switch to using H5O_layout_t for storing it, which
simplifies things considerably.

	Also, fix many compiler warnings.

Tested on:
	FreeBSD/32 6.3 (duty) in debug mode
	(Original patch tested on many machines)