Add three catalog setups, for UK mirror

The fgaddon-catalog was duplicated to avoid disturbing Curt’s config
he runs locally, until the new setup is working.

catalog/legacy-catalog/template.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--Template catalog - copy and modify for your site as required-->
+<PropertyList>
+  <template>
+    <version n="0">3.4.*</version>
+    <version n="1">3.5.*</version>
+    <version n="2">3.6.*</version>
+    <version n="3">3.7.*</version>
+    <version n="5">2016.*.*</version>
+    <version n="6">2017.*.*</version>
+    <id>org.flightgear.fgaddon.legacy</id>
+    <license>GPL</license>
+    <url>http://mirrors.ibiblio.org/flightgear/ftp/Aircraft-legacy/catalog.xml</url>
+    <name>FlightGear aircraft(legacy support)</name>
+    <description>This hangar provides aircraft officially supported and maintained by the 
+    FlightGear project, under a free-software license. Aircraft are intended for
+    use with FlightGear versions from 2017 and older.</description>
+
+    <alternate-version>
+      <version>2019.*</version>
+      <url>http://mirrors.ibiblio.org/flightgear/ftp/Aircraft/catalog.xml</url>
+      <id>org.flightgear.fgaddon</id>
+    </alternate-version>
+
+    <alternate-version>
+      <version>2018.*</version>
+      <url>http://mirrors.ibiblio.org/flightgear/ftp/Aircraft-2018/catalog.xml</url>
+      <id>org.flightgear.fgaddon.stable_2018</id>
+    </alternate-version>
+
+  </template>
+</PropertyList>