More docs for python 3 support.

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+=====================================================
+Supporting both Python 2 and Python 3 with Distribute
+=====================================================
+
+Starting with version 0.6.2, Distribute supports Python 3. Installing and
+using distribute for Python 3 code works exactly the same as for Python 2
+code, but Distribute also helps you to support Python 2 and Python 3 from
+the same source code by letting you run 2to3 on the code as a part of the
+build process. by setting the keyword parameter ``run_2to3`` to True.
+
+
+Distrubute as help during porting
+=================================
+
+Distribute can make the porting process much easier by automatically running
+2to3 as a part of the test running. To do this you need to configure the
+setup.py so that you can run the unit tests with ``python setup.py test``.
+
+See :ref:`test` for more information on this.
+
+Once you have the tests running under Python 2, you can add the run_2to3
+keyword parameters to setup(), and start running the tests under Python 3.
+The test command will now first run the build command during which the code
+will be converted with 2to3, and the tests will then be run from the build
+directory, as opposed from the source directory as is normally done.
+
+Distribute will convert all Python files, and also all doctests in Python
+files. However, if you have doctests located in separate text files, these
+will not automatically be converted. By adding them to the 
+``convert_doctests_2to3`` keyword parameter Distrubute will convert them as 
+well. 
+
+By default, the conversion uses all fixers in the ``lib2to3.fixers`` package.
+To use additional fixes, the parameter ``additional_2to3_fixers`` can be set
+to a list of names of packages containing fixers.
+
+A typical setup.py can look something like this::
+
+      from setuptools import setup
+      
+      setup(name='your.module',
+            version = '1.0',
+            description='This is your awesome module',
+            author='You',
+            author_email='your@email',
+            package_dir = {'': 'src'},
+            packages = ['your', 'you.module'],
+            test_suite = 'your.module.tests',
+            run_2to3 = True,
+            convert_doctests_2to3 = ['src/your/module/README.txt'],
+            additional_2to3_fixers = ['your.fixers']
+            )
+
+Differential conversion
+-----------------------
+
+Note that a file will only be copied and converted during the build process
+if the source file has been changed. If you add a file to the doctests
+that should be converted, it will not be converted the next time you run
+the tests, since it hasn't been modified. You need to remove it from the 
+build directory. Also if you run the build, install or test commands before
+adding the run_2to3 parameter, you will have to remove the build directory
+before you run the test command, as the files otherwise will seem updated, 
+and no conversion will happen.
+
+In general, if code doesn't seem to be converted, deleting the build directory
+and trying again is a good saferguard against the build directory getting
+"out of sync" with teh source directory.
+
+Distributing Python 3 modules
+=============================
+
+You can distribute your modules with Python 3 support in different ways. A
+normal source distribution will work, but can be slow in installing, as the
+2to3 process will be run during the install. But you can also distribute
+the module in binary format, such as a binary egg. That egg will contain the
+already converted code, and hence no 2to3 conversion is needed during install.
+
+Advanced features
+=================
+
+If certain fixers are to be suppressed, this again can be overridden with the
+list ``setuptools.commands.build_py.build_py.fixers``, which then contains the
+list of all fixer class names.
+
+If you don't want to run the 2to3 conversion on the doctests in Python files,
+you can turn that off by setting ``setuptools.run_2to3_on_doctests = False``.
+
+Note on compatibility with setuptools
+=====================================
+
+Setuptools do not know about the new keyword parameters to support Python 3.
+As a result it will warn about the unknown keyword parameters if you use
+setuptools instead of Distribute under Python 2. This is not an error, and
+install process will continue as normal, but if you want to get rid of that
+error this is easy. Simply conditionally add the new parameters into an extra 
+dict and pass that dict into setup()::
+
+      from setuptools import setup
+      import sys
+      
+      extra = {}
+      if sys.version_info >= (3,):
+          extra['run_2to3'] = True
+          extra['convert_doctests_2to3'] = ['src/your/module/README.txt']
+          extra['additional_2to3_fixers'] = ['your.fixers']
+      
+      setup(name='your.module',
+            version = '1.0',
+            description='This is your awesome module',
+            author='You',
+            author_email='your@email',
+            package_dir = {'': 'src'},
+            packages = ['your', 'you.module'],
+            test_suite = 'your.module.tests',
+            **extra
+            )
+
+This way the parameters will only be used under Python 3, where you have to
+use Distribute.