Add dates to changelog. Also add last Non-SM release, for comparison

CHANGELOG

@@ -1,4 +1,4 @@
-1.4
+1.4 / 2020-07-15
 Add documentation and manpages.
 
 Legacy-GUI:
@@ -23,14 +23,16 @@ nsm.h
  :optional-gui: support to nsm.h, for other applications to include and use. (Meyer, Hermann / brummer )
 
 
-1.3.2
+1.3.2 / 2020-06-20
 Rename new-session-manager executable to nsm-legacy-gui to prevent future confusion.
 
-1.3.1
+
+1.3.1 / 2020-06-20
 Add header copyright even to unchanged files to adhere to stricter packaging requirements.
 Meson can now switch off individual executables and will stop/error when trying to build without dependencies.
 
-1.3
+
+1.3 / 2020-06-17
 Rebranding to "new session manager"
 Upstream GUI tools "non-session-manager" and "nsm-proxy" converted to standard FLTK instead of a custom toolkit
 Changed build system to meson
@@ -38,5 +40,11 @@ License upgraded to GPLv3
 Simplified file structure
 Fix compiler warnings.
 
-1.2.1
+
+1.2.1 / 2020-04-19
 Current state of upstream Non Session Manager v1.2 including unreleased /nsm/gui/session/root
+
+
+1.1.0 / 2012-03-03
+Last release of Non-Session-Manager.
+https://non.tuxfamily.org/wiki/2012-03-03%20Release%20Announcement%20v1.1.0