Remove the python3 porting mode from the codebase

It's possible to use the python3 porting checker from
an older pylint version. But it's not evolving anymore
and was costing resource to maintain.

ChangeLog

@@ -10,6 +10,9 @@ Release date: TBA
 ..
   Put new features here and also in 'doc/whatsnew/2.11.rst'
 
+* The python3 porting mode checker and it's ``py3k`` option were removed. You can still find it in older pylint
+  versions.
+
 * Added new extension ``SetMembershipChecker`` with ``use-set-for-membership`` check:
   Emitted when using an in-place defined ``list`` or ``tuple`` to do a membership test. ``sets`` are better optimized for that.
 

doc/faq.rst

@@ -192,9 +192,7 @@ tricks like: ::
 
 pylint does have some messages disabled by default, either because
 they are prone to false positives or that they are opinionated enough
-for not being included as default messages. But most of the disabled
-messages are from the Python 3 porting checker, which is disabled by
-default. It needs special activation with the ``--py3k`` flag.
+for not being included as default messages.
 
 You can see the plugin you need to explicitly `load in the technical reference`_
 

examples/pylintrc

@@ -69,85 +69,14 @@ confidence=
 # --enable=similarities". If you want to run only the classes checker, but have
 # no Warning level messages displayed, use "--disable=all --enable=classes
 # --disable=W".
-disable=print-statement,
-        parameter-unpacking,
-        unpacking-in-except,
-        old-raise-syntax,
-        backtick,
-        long-suffix,
-        old-ne-operator,
-        old-octal-literal,
-        import-star-module-level,
-        non-ascii-bytes-literal,
-        raw-checker-failed,
+disable=raw-checker-failed,
         bad-inline-option,
         locally-disabled,
         file-ignored,
         suppressed-message,
         useless-suppression,
         deprecated-pragma,
         use-symbolic-message-instead,
-        apply-builtin,
-        basestring-builtin,
-        buffer-builtin,
-        cmp-builtin,
-        coerce-builtin,
-        execfile-builtin,
-        file-builtin,
-        long-builtin,
-        raw_input-builtin,
-        reduce-builtin,
-        standarderror-builtin,
-        unicode-builtin,
-        xrange-builtin,
-        coerce-method,
-        delslice-method,
-        getslice-method,
-        setslice-method,
-        no-absolute-import,
-        old-division,
-        dict-iter-method,
-        dict-view-method,
-        next-method-called,
-        metaclass-assignment,
-        indexing-exception,
-        raising-string,
-        reload-builtin,
-        oct-method,
-        hex-method,
-        nonzero-method,
-        cmp-method,
-        input-builtin,
-        round-builtin,
-        intern-builtin,
-        unichr-builtin,
-        map-builtin-not-iterating,
-        zip-builtin-not-iterating,
-        range-builtin-not-iterating,
-        filter-builtin-not-iterating,
-        using-cmp-argument,
-        eq-without-hash,
-        div-method,
-        idiv-method,
-        rdiv-method,
-        exception-message-attribute,
-        invalid-str-codec,
-        sys-max-int,
-        bad-python3-import,
-        deprecated-string-function,
-        deprecated-str-translate-call,
-        deprecated-itertools-function,
-        deprecated-types-field,
-        next-method-defined,
-        dict-items-not-iterating,
-        dict-keys-not-iterating,
-        dict-values-not-iterating,
-        deprecated-operator-function,
-        deprecated-urllib-function,
-        xreadlines-attribute,
-        deprecated-sys-function,
-        exception-escape,
-        comprehension-escape
 
 # Enable the message, report, category or checker with the given id(s). You can
 # either give multiple identifier separated by comma (,) or put this option