[svn-r22105] Description:

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

tools/h5diff/testfiles/h5diff_640.txt

@@ -0,0 +1,4 @@
+h5diff error: -d, -p and --use-system-epsilon options are mutually-exclusive;
+use no more than one.
+Try '-h' or '--help' option for more information or see the h5diff entry in the 'HDF5 Reference Manual'.
+EXIT CODE: 1