Add server-side map rendering component.

Based on our own fork of leaflet-headless.

lib/www/server/lib/map/index.js

@@ -0,0 +1,22 @@
+const L = require('leaflet-headless');
+
+function leafletMap (cfg) {
+
+	const container = document.createElement("div");
+	container.style.setProperty("background-color", "transparent");
+	let map = L.map(container);
+
+	const bbox = cfg.bbox || L.geoJSON(cfg.layers.map(i => i.features)).getBounds();
+	map.fitBounds(bbox);
+	map.setSize(cfg.size?.width || 500, cfg.size?.height || 500);
+	
+	for (let layer of cfg.layers) {
+		L.geoJSON(layer.features, layer.options).addTo(map);
+	}
+	
+	map.fitBounds(bbox); // again
+
+	return map;
+}
+
+module.exports = leafletMap;

lib/www/server/package.json

@@ -14,6 +14,7 @@
     "express": "^4.17.1",
     "express-jwt": "^6.0.0",
     "jsonwebtoken": "^8.5.1",
+    "leaflet-headless": "gitlab:aaltronav/contrib/leaflet-headless#devel",
     "marked": "^2.0.3",
     "netmask": "^1.0.6",
     "node-fetch": "^2.6.1",