Add module for Python 3 compatibility layer.

IPython/utils/py3compat.py

@@ -0,0 +1,37 b''
+import sys
+
+def no_code(x, encoding=None):
+    return x
+
+def decode(s, encoding=None):
+    encoding = encoding or sys.stdin.encoding or sys.getdefaultencoding()
+    return s.decode(encoding, "replace")
+
+def encode(u, encoding=None):
+    encoding = encoding or sys.stdin.encoding or sys.getdefaultencoding()
+    return u.encode(encoding, "replace")
+
+if sys.version_info[0] >= 3:
+    PY3 = True
+    
+    input = input
+    builtin_mod_name = "builtins"
+    
+    str_to_unicode = no_code
+    unicode_to_str = no_code
+    str_to_bytes = encode
+    bytes_to_str = decode
+    
+else:
+    PY3 = False
+    
+    input = raw_input
+    builtin_mod_name = "__builtin__"
+    
+    str_to_unicode = decode
+    unicode_to_str = encode
+    str_to_bytes = no_code
+    bytes_to_str = no_code
+
+def execfile(fname, glob, loc):
+    exec compile(open(fname).read(), fname, 'exec') in glob, loc