Bring r20557:22085 from trunk to this branch, also fixing some other
issues/failures in the branch simultaneously. The h5repack tests are still
failing, but Neil will be checking into those, so the branch can be fully
functional again.
Tested on:
Mac OSX/64 10.7.3 (amazon) w/debug
Description: Improved external link traversal of h5dump. h5dump will now
properly avoid all cycles, even those spanning multiple files. Improvement
to the output of committed datatypes. Committed datatypes are now checked
for uniqueness (like other objects). Tests added for these cases.
Tested: kagiso, linew, smirom (h5committest)
