hdf5_msb

[svn-r720] Changes since 19980922
----------------------

./src/H5F.c
./src/H5Fprivate.h
./src/H5P.c
./src/H5Ppublic.h
./test/chunk.c
./test/dsets.c
	The number of slots in the raw data cache can be queried or
	set with H5Pget/set_cache(), which now take an extra argument.
	The default number of slots is 521 and the default maximum
	size is 1MB.

./src/H5Fistore.c
./src/H5Fprivate.h
	Finished optimizations.  The cache is now a hash and a linked
	list instead of an array.  The cpu time on my machine for
	H5F_istore_lock() has been cut by 60% and H5F_istore_unlock() by
	35%.