Work for bugzilla 1754: h5diff: support comparing through links.
Description:
merged from hdf5 trunk (18164, 18165, 18166, 18167, 18170, 18266, 18273)
Tested:
h5committest (jam, amani and linew)
#1368 (E1) h5diff: implement "not comparable" messages. Implemented RFC. The new option is <-c, --compare List objects that are not comparable>
added some test cases
tested: windows, linux