Merge all of my changes from merge-back-to-feature-vfd_swmr-attempt-1,

including the merge of `hdffv/hdf5/develop`, back to the branch that Vailin and
I share.

Now I need to put this branch on a fork with a less confusing name than
vchoi_fork!

tools/testfiles/pbits/tpbitsLengthPositive.ddl

@@ -12,6 +12,16 @@ usage: h5dump [OPTIONS] files
      -b B, --binary=B     Binary file output, of form B
      -O F, --ddl=F        Output ddl text into file F
                           Use blank(empty) filename F to suppress ddl display
+     --s3-cred=<cred>     Supply S3 authentication information to "ros3" vfd.
+                          <cred> :: "(<aws-region>,<access-id>,<access-key>)"
+                          If absent or <cred> -> "(,,)", no authentication.
+                          Has no effect is filedriver is not `ros3'.
+     --hdfs-attrs=<attrs> Supply configuration information for HDFS file access.
+                          For use with "--filedriver=hdfs"
+                          <attrs> :: (<namenode name>,<namenode port>,
+                                      <kerberos cache path>,<username>,
+                                      <buffer size>)
+                          Any absent attribute will use a default value.
 --------------- Object Options ---------------
      -a P, --attribute=P  Print the specified attribute
                           If an attribute name contains a slash (/), escape the
@@ -135,4 +145,3 @@ usage: h5dump [OPTIONS] files
 
       h5dump -d /foo -f family fam%05d.h5
 
-h5dump error: Packed Bit length value(0) must be positive.