Merging the py3k-pep3137 branch back into the py3k branch.

No detailed change log; just check out the change log for the py3k-pep3137
branch.  The most obvious changes:

  - str8 renamed to bytes (PyString at the C level);
  - bytes renamed to buffer (PyBytes at the C level);
  - PyString and PyUnicode are no longer compatible.

I.e. we now have an immutable bytes type and a mutable bytes type.

The behavior of PyString was modified quite a bit, to make it more
bytes-like.  Some changes are still on the to-do list.

Doc/library/array.rst

@@ -56,8 +56,9 @@ The module defines the following type:
 .. function:: array(typecode[, initializer])
 
    Return a new array whose items are restricted by *typecode*, and initialized
-   from the optional *initializer* value, which must be a list, string, or iterable
-   over elements of the appropriate type.
+   from the optional *initializer* value, which must be a list, object
+   supporting the buffer interface, or iterable over elements of the 
+   appropriate type.
 
    If given a list or string, the initializer is passed to the new array's
    :meth:`fromlist`, :meth:`fromstring`, or :meth:`fromunicode` method (see below)
@@ -69,6 +70,10 @@ The module defines the following type:
 
    Obsolete alias for :func:`array`.
 
+.. data:: typecodes
+
+   A string with all available type codes.
+
 Array objects support the ordinary sequence operations of indexing, slicing,
 concatenation, and multiplication.  When using slice assignment, the assigned
 value must be an array object with the same type code; in all other cases,

Doc/library/exceptions.rst

@@ -405,7 +405,11 @@ module for more information.
 
    Base class for warnings related to Unicode.
 
+.. exception:: BytesWarning
+
+   Base class for warnings related to :class:`bytes` and :class:`buffer`.
+
+
 The class hierarchy for built-in exceptions is:
 
-
 .. literalinclude:: ../../Lib/test/exception_hierarchy.txt

Doc/library/functions.rst

@@ -118,18 +118,19 @@ available.  They are listed here in alphabetical order.
    .. index:: pair: Boolean; type
 
 
-.. function:: bytes([arg[, encoding[, errors]]])
+.. function:: buffer([arg[, encoding[, errors]]])
 
-   Return a new array of bytes.  The :class:`bytes` type is a mutable sequence
+   Return a new array of bytes.  The :class:`buffer` type is an immutable sequence
    of integers in the range 0 <= x < 256.  It has most of the usual methods of
-   mutable sequences, described in :ref:`typesseq-mutable`, as well as a few
-   methods borrowed from strings, described in :ref:`bytes-methods`.
+   mutable sequences, described in :ref:`typesseq-mutable`, as well as most methods
+   that the :class:`str` type has, see :ref:`bytes-methods`.
 
    The optional *arg* parameter can be used to initialize the array in a few
    different ways:
 
    * If it is a *string*, you must also give the *encoding* (and optionally,
-     *errors*) parameters; :func:`bytes` then acts like :meth:`str.encode`.
+     *errors*) parameters; :func:`buffer` then converts the Unicode string to
+     bytes using :meth:`str.encode`.
 
    * If it is an *integer*, the array will have that size and will be
      initialized with null bytes.
@@ -137,12 +138,24 @@ available.  They are listed here in alphabetical order.
    * If it is an object conforming to the *buffer* interface, a read-only buffer
      of the object will be used to initialize the bytes array.
 
-   * If it is an *iterable*, it must be an iterable of integers in the range 0
-     <= x < 256, which are used as the initial contents of the array.
+   * If it is an *iterable*, it must be an iterable of integers in the range
+     ``0 <= x < 256``, which are used as the initial contents of the array.
 
    Without an argument, an array of size 0 is created.
 
 
+.. function:: bytes([arg[, encoding[, errors]]])
+
+   Return a new "bytes" object, which is an immutable sequence of integers in
+   the range ``0 <= x < 256``.  :class:`bytes` is an immutable version of
+   :class:`buffer` -- it has the same non-mutating methods and the same indexing
+   and slicing behavior.
+   
+   Accordingly, constructor arguments are interpreted as for :func:`buffer`.
+
+   Bytes objects can also be created with literals, see :ref:`strings`.
+
+
 .. function:: chr(i)
 
    Return the string of one character whose Unicode codepoint is the integer

Doc/library/stdtypes.rst

@@ -1313,9 +1313,11 @@ Bytes and Buffer Methods
 
 Bytes and buffer objects, being "strings of bytes", have all methods found on
 strings, with the exception of :func:`encode`, :func:`format` and
-:func:`isidentifier`, which do not make sense with these types.  Wherever one of
-these methods needs to interpret the bytes as characters (e.g. the :func:`is...`
-methods), the ASCII character set is assumed.
+:func:`isidentifier`, which do not make sense with these types.  For converting
+the objects to strings, they have a :func:`decode` method.
+
+Wherever one of these methods needs to interpret the bytes as characters
+(e.g. the :func:`is...` methods), the ASCII character set is assumed.
 
 .. note::
 

Doc/library/warnings.rst

@@ -80,6 +80,10 @@ following warnings category classes are currently defined:
 | :exc:`UnicodeWarning`            | Base category for warnings related to         |
 |                                  | Unicode.                                      |
 +----------------------------------+-----------------------------------------------+
+| :exc:`BytesWarning`              | Base category for warnings related to         |
+|                                  | :class:`bytes` and :class:`buffer`.           |
++----------------------------------+-----------------------------------------------+
+
 
 While these are technically built-in exceptions, they are documented here,
 because conceptually they belong to the warnings mechanism.