This started opening files in text mode by default in the 2.3 release,
which is a disaster on Windows.  Restored the binary default of all
previous releases.  Also minor code cleanups.

Bugfix candidate!
diff --git a/Misc/NEWS b/Misc/NEWS
index 8f24d85..ebda27d 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -52,6 +52,12 @@
 Tools/Demos
 -----------
 
+- md5sum.py mistakenly opened input files in text mode by default, a
+  silent and dangerous change from previous releases.  It once again
+  opens input files in binary mode by default.  The -t and -b flags
+  remain for compatibility with the 2.3 release, but -b is the default
+  now.
+
 - py-electric-colon now works when pending-delete/delete-selection mode is
   in effect