Add 3.0.12 release notes and date

[skip ci]

ANNOUNCE

@@ -1,4 +1,4 @@
-*** ANNOUNCE: SWIG 3.0.12 (in progress) ***
+*** ANNOUNCE: SWIG 3.0.12 (27 Jan 2017) ***
 
 http://www.swig.org
 

CHANGES.current

@@ -4,7 +4,7 @@ See the RELEASENOTES file for a summary of changes in each release.
 Issue # numbers mentioned below can be found on Github. For more details, add
 the issue number to the end of the URL: https://github.com/swig/swig/issues/
 
-Version 3.0.12 (in progress)
+Version 3.0.12 (27 Jan 2017)
 ============================
 
 2017-01-24: andrey-starodubtsev

Doc/Manual/Sections.html

@@ -8,7 +8,7 @@
 <H1><a name="Sections">SWIG-3.0 Documentation</a></H1>
 
 <p>
-Last update : SWIG-3.0.12 (in progress)
+Last update : SWIG-3.0.12 (27 Jan 2017)
 </p>
 
 <H2><a name="Sections_Sections">Sections</a></H2>

README

@@ -1,6 +1,6 @@
 SWIG (Simplified Wrapper and Interface Generator)
 
-Version: 3.0.12 (in progress)
+Version: 3.0.12 (27 Jan 2017)
 
 Tagline: SWIG is a compiler that integrates C and C++ with languages
          including Perl, Python, Tcl, Ruby, PHP, Java, C#, D, Go, Lua,

RELEASENOTES

@@ -7,6 +7,11 @@ Release Notes
 Detailed release notes are available with the release and are also
 published on the SWIG web site at http://swig.org/release.html.
 
+SWIG-3.0.12 summary:
+- Add support for Octave-4.2.
+- Enhance %extend to support template functions.
+- Language specific enhancements and fixes for C#, D, Java, PHP7.
+
 SWIG-3.0.11 summary:
 - PHP 7 support added.
 - C++11 alias templates and type aliasing support added.