vchoi_fork

[svn-r4696] 
Purpose:
    Modify H5Fclose behavior
Description:
    The HDF5 actual file close behaves in several ways in terms of if there
    are still objects(dataset, group, datatype) opened in file.
Solution:
    Added a new file access property, file close degree.  It has four values,
	H5F_CLOSE_DEFAULT
	H5F_CLOSE_WEAK
	H5F_CLOSE_SEMI
	H5F_CLOSE_STRONG
    The way a file is closed is decided by these values.
Platforms tested:
    IRIX64 6.5, SunOS 5.6, FreeBSD 4.4