add tileset splitDirection

modules/overlay/model/Tileset.js

     return this
   }
 
+  /**
+   *
+   * @param splitDirection
+   * @return {Tileset}
+   */
+  setSplitDirection(splitDirection) {
+    this.readyPromise.then(tileset => {
+      tileset.splitDirection = splitDirection
+    })
+    return this
+  }
+
   /**
    * Sets style
    * @param style

modules/themes/index.js

 import './tooltip.scss'
 import './contextmenu.scss'
 import './mapswitch.scss'
-import './mapsplit.scss'
+import './slider.scss'
 import './hawkeyemap.scss'
 import './compass.scss'
 import './locationbar.scss'