Bump version number to 3.7.1 and finalize documentation

Updated version number in gf.cabal and update debian/changelog
News item on home page (index.html)
Some last minute edits on the download page
Move the new release notes and download page in place.

index.html

@@ -26,7 +26,7 @@ function sitesearch() {
 <img class="gflogo" src="doc/Logos/gf1.svg" alt="">
 <H1>Grammatical Framework</H1>
   <small class=tagline>A programming language for multilingual grammar applications</small>
-<!--<p>Version 3.7<br>June 2015-->
+<!--<p>Version 3.7.1<br>Oct 2015-->
 </div>
 
 <div class=menu>
@@ -113,6 +113,8 @@ document.write('<div style="float: right; margin-top: 3ex;">  <form onsubmit="re
 <div class=news2>
 
 <table class=news>
+<tr><td>2015-10-02:<td><strong>GF 3.7.1 released!</strong>
+    <a href="download/release-3.7.1.html">Release notes</a>.
 <tr><td>2015-06-25:<td><strong>GF 3.7 released!</strong>
     <a href="download/release-3.7.html">Release notes</a>.
 <tr><td>2015-03-13:<td>New resource grammar language: Mongolian.