[svn-r7435] Purpose:

Bug Fix and code cleanup

Description:
    Correct error in H5T_detect_class that was causing nested compound datatypes
with to not detect the datatype class of fields correctly, which caused errors
with fill-values, variable-length datatypes and chunks later on.

    Return the rank of the array datatype from H5Tget_array_dims(), like
H5Sget_dims().

    Lots of cleanups to datatype code, to make the handling of arrays, compound
types, variable-length strings and sequences and enumerated types more
consistent and robust.

Platforms tested:
    FreeBSD 4.9 (sleipnir)
    h5committest

doc/html/RM_H5T.html

@@ -2946,13 +2946,13 @@ zero.
 <dl>
 <dt><strong>Name:</strong> <a name="Datatype-GetArrayDims">H5Tget_array_dims</a>
 <dt><strong>Signature:</strong>
-    <dd><em>herr_t</em> <code>H5Tget_array_dims</code>(
+    <dd><em>int</em> <code>H5Tget_array_dims</code>(
                        <em>hid_t</em> <code>adtype_id</code>,
                        <em>hsize_t *</em><code>dims[]</code>,
                        <em>int *</em><code>perm[]</code>
     )
 <dt><strong>Purpose:</strong>
-    <dd>Returns sizes of array dimensions and dimension permutations.
+    <dd>Retrieves sizes of array dimensions and dimension permutations.
 <dt><strong>Description:</strong>
     <dd><code>H5Tget_array_dims</code> returns the sizes of the dimensions
         and the dimension permutations of the specified array datatype object.
@@ -2970,7 +2970,7 @@ zero.
             <dd>OUT: Dimension permutations.
     </dl>
 <dt><strong>Returns:</strong>
-    <dd>Returns a non-negative value if successful;
+    <dd>Returns the non-negative number of dimensions of the array type if successful;
         otherwise returns a negative value.
 <dt><strong>Non-C API(s):</strong>
     <dd><a href="fortran/h5t_FORTRAN.html#h5tget_array_dims_f"