Add baseurl feature

Allow an optional base url to be included in generation of html files.

templates/page.tpl.html

@@ -2,6 +2,9 @@
 <html lang="en">
 <head>
   <title>Hacker Public Radio ~ The Technology Community Podcast</title>
+  <!--% IF baseurl %-->
+  <base href="<!--% baseurl %-->">
+  <!--% END %-->
   <meta charset="utf-8" />
   <meta http-equiv="X-Clacks-Overhead" content="GNU Terry Pratchett" />
   <meta name="keywords" content="Technology, Tech News, Education, Training" />