Fixes issue 1571:

Adding missing close for open.
If the "close()" call is missing after a "open(filename)" call, the filename isn't guaranteed to be closed before the interpreter exits.
This is generally a bad practice as explained here: https://stackoverflow.com/questions/7395542/is-explicitly-closing-files-important

Also replaced "fid=open(filename) fid.close()" statements for files with the safer
"with open(filename) as fid:" blocks. See https://www.python.org/dev/peps/pep-0343/

bin/make-new-unittest-file.py

@@ -52,9 +52,9 @@ def writeFile(filename, stub, values):
     if os.path.exists(filename):
         print("'%s' already exists. Exiting." % filename)
         sys.exit(1)
-    output = open(filename, 'w')
-    output.write(stub % values)
-    output.close()
+    with open(filename, 'w') as output:
+        output.write(stub % values)
+
     print("Wrote %s" % filename)