Added the maps-module to the iwmlib.

Migrated a  ot of the content from the tuesch to the iwmlib.
This is before the decoupeling of the layers.

lib/pixi/maps/projections/mercator.js

@@ -0,0 +1,43 @@
+import Projection from './projection.js'
+
+/**
+ * This is a projection file, that grants access to the
+ * MERCATOR projection.
+ *
+ * Regulary only few Projections will be used in one
+ * project, therefore only required one's should be
+ * loaded.
+ */
+
+export default class Mercator extends Projection {
+    forward(coords) {
+        let lat = coords.x
+        let lng = coords.y
+
+        const PI_180 = Math.PI / 180.0
+        const PI_4 = Math.PI * 4
+
+        const sinLatitude = Math.sin(lat * PI_180)
+        let y = 0.5 - Math.log((1 + sinLatitude) / (1 - sinLatitude)) / PI_4
+        let x = (lng + 180) / 360
+
+        y = y < 0 ? 0 : y > 1 ? 1 : y
+
+        return new PIXI.Point(x, y)
+    }
+
+    backward(point) {
+        let lng = point.x * 360 - 180
+        let lat = (Math.asin(-2 / (Math.exp(4 * Math.PI * (0.5 - point.y)) + 1) + 1) * 180) / Math.PI
+
+        return new PIXI.Point(lat, lng)
+    }
+
+    toString() {
+        return 'Mercator Projection'
+    }
+
+    get maxViewport() {
+        return { min: new PIXI.Point(-85, -180), max: new PIXI.Point(85, 180) }
+    }
+}