hdf5

[svn-r15131] Description:
	Finish omnibus chunked dataset I/O refactoring, to separate general
actions on chunked datasets from actions that are specific to using the v1
B-tree index.

	Cleaned up a few bugs and added some additional tests also.

Tested on:
        FreeBSD/32 6.2 (duty) in debug mode
        FreeBSD/64 6.2 (liberty) w/C++ & FORTRAN, in debug mode
        Linux/32 2.6 (kagiso) w/PGI compilers, w/C++ & FORTRAN, w/threadsafe,
                                in debug mode
        Linux/64-amd64 2.6 (smirom) w/default API=1.6.x, w/C++ & FORTRAN,
                                in production mode
        Linux/64-ia64 2.6 (cobalt) w/Intel compilers, w/C++ & FORTRAN,
                                in production mode
        Solaris/32 2.10 (linew) w/deprecated symbols disabled, w/C++ & FORTRAN,
                                w/szip filter, in production mode
        Mac OS X/32 10.5.2 (amazon) in debug mode
        Linux/64-ia64 2.4 (tg-login3) w/parallel, w/FORTRAN, in production mode