Update the code to better reflect recommended style:

Use != instead of <> since <> is documented as "obsolescent".
Use "is" and "is not" when comparing with None or type objects.
diff --git a/Lib/lib-old/grep.py b/Lib/lib-old/grep.py
index 423c065..6f74fd3 100644
--- a/Lib/lib-old/grep.py
+++ b/Lib/lib-old/grep.py
@@ -73,7 +73,7 @@
 		else:
 			prefix = ' ' * len(prefix)
 			for c in line:
-				if c <> '\t': c = ' '
+				if c != '\t': c = ' '
 				prefix = prefix + c
 		if start == end: prefix = prefix + '\\'
 		else: prefix = prefix + '^'*(end-start)