Adds stand alone _md5 and _sha1 modules for use by hashlib on systems

when the OpenSSL library is either not present or not found by setup.py.

These are derived from the public domain libtomcrypt (libtom.org) just like
the existing sha256 and sha512 modules.

Lib/hashlib.py

@@ -10,8 +10,8 @@ new(name, data=b'') - returns a new hash object implementing the
                       given hash function; initializing the hash
                       using the given binary data.
 
-Named constructor functions are also available, these are much faster
-than using new():
+Named constructor functions are also available, these are faster
+than using new(name):
 
 md5(), sha1(), sha224(), sha256(), sha384(), and sha512()
 
@@ -22,14 +22,13 @@ Choose your hash function wisely.  Some have known collision weaknesses.
 sha384 and sha512 will be slow on 32 bit platforms.
 
 Hash objects have these methods:
- - update(arg): Update the hash object with the string arg. Repeated calls
+ - update(arg): Update the hash object with the bytes in arg. Repeated calls
                 are equivalent to a single call with the concatenation of all
                 the arguments.
- - digest():    Return the digest of the strings passed to the update() method
-                so far. This may contain non-ASCII characters, including
-                NUL bytes.
- - hexdigest(): Like digest() except the digest is returned as a string of
-                double length, containing only hexadecimal digits.
+ - digest():    Return the digest of the bytes passed to the update() method
+                so far.
+ - hexdigest(): Like digest() except the digest is returned as a unicode
+                object of double length, containing only hexadecimal digits.
  - copy():      Return a copy (clone) of the hash object. This can be used to
                 efficiently compute the digests of strings that share a common
                 initial substring.
@@ -54,11 +53,11 @@ More condensed:
 
 def __get_builtin_constructor(name):
     if name in ('SHA1', 'sha1'):
-        import _sha
-        return _sha.new
+        import _sha1
+        return _sha1.sha1
     elif name in ('MD5', 'md5'):
         import _md5
-        return _md5.new
+        return _md5.md5
     elif name in ('SHA256', 'sha256', 'SHA224', 'sha224'):
         import _sha256
         bs = name[3:]
@@ -78,7 +77,7 @@ def __get_builtin_constructor(name):
 
 
 def __py_new(name, data=b''):
-    """new(name, data='') - Return a new hashing object using the named algorithm;
+    """new(name, data=b'') - Return a new hashing object using the named algorithm;
     optionally initialized with data (which must be bytes).
     """
     return __get_builtin_constructor(name)(data)