Update release date and update ANNOUNCE.txt with new items

CHANGES.rst

@@ -10,7 +10,7 @@ wxPython Changelog
 
 4.0.0 "The Phoenix Takes Flight!"
 ---------------------------------
-* 27-Jan-2018
+* 31-Jan-2018
 
 PyPI:   https://pypi.python.org/pypi/wxPython/4.0.0
 Extras: https://extras.wxPython.org/wxPython4/extras/
@@ -80,7 +80,6 @@ Changes in this release include the following:
   broken and the saved reference is deleted after the timer expires and the
   callable has been called. (#457)
 
-
 * Although it's more or less just an implementation detail, add wrappers for
   wx.aui.AuiTabCtrl so references to it will get the correct type. (#664)
 
@@ -130,6 +129,7 @@ Changes in this release include the following:
 
 
 
+
 4.0.0b2 -- "Hurricanes, Floods, and Forest Fires! Oh My!"
 ---------------------------------------------------------
 * 16-Sept-2017

packaging/ANNOUNCE.txt

@@ -79,7 +79,6 @@ Changes in this release include the following:
   broken and the saved reference is deleted after the timer expires and the
   callable has been called. (#457)
 
-
 * Although it's more or less just an implementation detail, add wrappers for
   wx.aui.AuiTabCtrl so references to it will get the correct type. (#664)
 
@@ -114,6 +113,19 @@ Changes in this release include the following:
 * Allow extra CLI args to be passed to build.py by setting WXPYTHON_BUILD_ARGS
   in the environment.
 
+* Added context manager methods to wx.DC that explicitly destroys the C++
+  part of the DC upon exit. Using DCs as context managers is not required, but
+  can be handy in the rare cases where something holds on to a DC for too
+  long, perhaps unintentionally. (#680)
+
+* Fixed crash due to too aggressive management of wxModules when we load
+  subordinate extensions that have their own wxModules (wx.html, wx.adv, etc.)
+  (#688)
+
+* Fixed StyledTextCtrl.MarkerDefineRGBAImage and RegisterRGBAImage methods to
+  be able to accept any Python buffer compatible object for the pixel data. (#716)
+
+