vchoi_fork

[svn-r336] Changes since 19980402
----------------------

./MANIFEST
./test/Makefile.in
./test/shtype.c		[NEW]
	Added some tests for shared data types.

./configure.in
	Removed MF and HL from the default debug list since.  MF
	because it hasn't been implemented yet and HL because it
	produces lots of annoying messages about adjusting the size of
	local heaps.

./src/H5F.c
./src/H5T.c
./src/H5Tprivate.h
	Fixed a bug with opening the same file twice.  The first close
	on the file_id incorrectly closed shared data structs.
	Closing a file now correctly unshares data types that might be
	pointing into that file.

./src/H5T.c
./src/H5Tpublic.h
	Added an H5Tis_shared().  The caller supplies a file and a
	data type and the function returns true if the data type is
	currently marked for sharing in that file.

./src/H5AC.c
./src/H5F.c
./src/H5HL.c
./src/H5HG.c
./src/H5MF.c
./src/H5O.c
	We now detect errors sooner when writing to a read-only
	file. In the past, the error might not show up until the
	cached item was flushed, and it was sometimes possible to not
	even get an error!

./src/H5I.c
./src/H5Iprivate.h
	If the search function fails then H5I_search() returns
	failure.  Also, the first argument for the search function
	isn't const anymore because we might want the search to have
	side effects (like calling H5T_unshare() for all shared data
	types whose file just closed).