Synchronize and expand what's new on 5.4

docs/source/whatsnew/version5.rst

@@ -5,10 +5,63 b''
 IPython 5.4
 ===========
 
+IPython 5.4-LTS is the first release of IPython after the release of the 6.x
+series which is Python 3 only. It backports most of the new exposed API
+additions made in IPython 6.0 and 6.1 and avoid having to write conditional
+logics depending of the version of IPython.
+
+Please upgrade to pip 9 or greater before upgrading IPython. 
+Failing to do so on Python 2 may lead to a broken IPython install.
+
+Configurable TerminalInteractiveShell
+-------------------------------------
+
+Backported from the 6.x branch as an exceptional new feature. See
+:ghpull:`10373` and :ghissue:`10364`
+
+IPython gained a new ``c.TerminalIPythonApp.interactive_shell_class`` option
+that allow to customize the class used to start the terminal frontend. This
+should allow user to use custom interfaces, like reviving the former readline
+interface which is now a separate package not maintained by the core team.
+
+
+Define ``_repr_mimebundle_``
+----------------------------
+
+Object can now define `_repr_mimebundle_` in place of multiple `_repr_*_`
+methods and return a full mimebundle. This greatly simplify many implementation
+and allow to publish custom mimetypes (like geojson, plotly, dataframes....).
+See the ``Cutom Display Logic`` example notebook for more informations.
+
+Execution Heuristics
+--------------------
+
+The heuristic for execution in the command line interface is now more biased
+toward executing for single statement. While in IPython 4.x and before a single
+line would be executed when enter is pressed, IPython 5.x would insert a new
+line. For single line statement this is not true anymore and if a single line is
+valid Python, IPython will execute it regardless of the cursor position. Use
+:kbd:`Ctrl-O` to insert a new line. :ghpull:`10489`
+
+
+Implement Display IDs
+---------------------
+
+Implement display id and ability to update a given display. This should greatly
+simplify a lot of code by removing the need for widgets and allow other frontend
+to implement things like progress-bars.  See :ghpull:`10048`
+
+Miscs
+-----
+
+* ``_mp_main_`` is not reloaded which fixes issues with multiprocessing.
+  :ghpull:`10523`
+* Use user colorscheme in Pdb as well :ghpull:`10479`
+* Faster shutdown. :ghpull:`10408` 
+* Fix a crash in reverse search. :ghpull:`10371`
 * added ``Completer.backslash_combining_completions`` boolean option to
   deactivate backslash-tab completion that may conflict with windows path. 
 
-
 IPython 5.3
 ===========
 
@@ -70,6 +123,9 b' Released on January 29th, 2017. Remarkable changes and fixes:'
 * Deprecate the ``%autoindent`` magic. :ghpull:`10176`
 * Emit a :any:`DeprecationWarning` when setting the deprecated
   ``limit_to_all`` option of the completer. :ghpull:`10198`
+* The :cellmagic:`capture` magic can now capture the result of a cell (from an
+  expression on the last line), as well as printed and displayed output.
+  :ghpull:`9851`.
 
 
 Changes of behavior to :any:`InteractiveShellEmbed`.