Add automatic binary file detection to diff and export Based on a patch by Fuming Wang - add util.binary which decides whether a file is binary if it has any NUL characters in the first 1K. - teach mdiff.unidiff to print "binary file <x> has changed" for binary files - add text flag to cause unidiff and dodiff to treat all files as text - add -a and --text flags (like diff(1)) to hg diff and export - update docs

--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -9,6 +9,11 @@ import os, errno
 from demandload import *
 demandload(globals(), "re")
 
+def binary(s):
+    if s and '\0' in s[:4096]:
+        return True
+    return False
+
 def unique(g):
     seen = {}
     for f in g: