Unify Directory listing, InitialWorkDir and secondaryFiles to accept equivalent

type.

Author: Peter Amstutz

draft-4/CommandLineTool.yml

@@ -646,7 +646,7 @@ $graph:
     - name: listing
       type:
         - type: array
-          items: DirentExt
+          items: [File, DirentExt]
         - string
         - Expression
       jsonldPredicate:

draft-4/Process.yml

@@ -225,7 +225,10 @@ $graph:
         _id: "cwl:path"
         _type: "@id"
     - name: listing
-      type: Dirent[]?
+      type:
+        - "null"
+        - type: array
+          items: [File, Dirent]
       doc: List of files or subdirectories contained in this directory
       jsonldPredicate:
         _id: "cwl:listing"