Add extractor for the Indico conference management system

That's used by LAS for example.

src/extractors/extractors.qrc

@@ -48,6 +48,8 @@
         <file>hotels.com.js</file>
         <file>iberia.json</file>
         <file>iberia.js</file>
+        <file>indico.json</file>
+        <file>indico.js</file>
         <file>indigo.json</file>
         <file>indigo.js</file>
         <file>irctc.json</file>

src/extractors/indico.js

+/*
+   SPDX-FileCopyrightText: 2020 Volker Krause <vkrause@kde.org>
+
+   SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+
+function parseRegistration(html) {
+    var res = JsonLd.newEventReservation();
+    res.reservationFor.name = html.eval('//h1')[0].content;
+    res.reservationNumber = html.eval('//h3/span')[0].content.match(/#(.*)/)[1];
+    res.modifyReservationUrl = html.eval('//a')[0].attribute('href');
+
+    var time = html.eval('//div/div/p/strong/..')[0].content.match(/\((.*)\s+-\s+(.*)\)/);
+    res.reservationFor.startDate = JsonLd.toDateTime(time[1], "dd MMM yyyy, hh:mm", "en");
+    res.reservationFor.endDate = JsonLd.toDateTime(time[2], "dd MMM yyyy, hh:mm", "en");
+
+    return res;
+}

src/extractors/indico.json

+{
+    "filter": [
+        {
+            "header": "Subject",
+            "match": "^\\[Indico\\] ",
+            "type": "Email"
+        }
+    ],
+    "function": "parseRegistration",
+    "script": "indico.js",
+    "type": "Html"
+}