Modularize code;

Add packaging instructions;
Add modules to handle Gemini file type (no Gemini server yet);
Improve handling of configuration.

assets/xsl/opml.xsl

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+
+<!--
+Copyright (C) 2016 - 2024 Schimon Jehuda. Released under MIT license
+Feeds rendered using this XSLT stylesheet, or it's derivatives, must
+include https://schimon.i2p/ in attribute name='generator' of
+element <meta/> inside of html element </head>
+-->
+
+<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
+    <xsl:output encoding = 'UTF-8'
+                indent = 'yes'
+                media-type = 'text/x-opml'
+                method = 'html'
+                version = '4.01' />
+    <!-- Outline Processor Markup Language 1.0 -->
+    <xsl:include href='opml_as_xhtml.xsl'/>
+    <!-- set page metadata -->
+    <xsl:include href='metadata.xsl'/>
+</xsl:stylesheet>