Add H5Rget_obj_type() to the API versioning and switch internal
routines to use H5Rget_obj_type2()
Misc. other code cleanups, etc.
Tested on:
FreeBSD/32 6.2 (duty)
FreeBSD/64 6.2 (liberty)
Linux/32 2.6 (kagiso)
Linux/64 2.6 (smirom)
AIX/32 5.3 (copper)
Solaris/32 2.10 (linew)
Mac OS X/32 10.4.10 (amazon)