feature request: implement support for overlays

[demokrit2017]

It would be just incredible, if you might be able to add support for overlays to combine e.g. Satellite views with labels, to generate HybridMaps. E.g.:

// https: also suppported. var Esri_WorldImagery = L.tileLayer('https://server.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer/tile/{z}/{y}/{x}', { attribution: 'Tiles © Esri — Source: Esri, i-cubed, USDA, USGS, AEX, GeoEye, Getmapping, Aerogrid, IGN, IGP, UPR-EGP, and the GIS User Community' }); // https: also suppported. var Hydda_RoadsAndLabels = L.tileLayer('https://{s}.tile.openstreetmap.se/hydda/roads_and_labels/{z}/{x}/{y}.png', { maxZoom: 18, attribution: 'Tiles courtesy of OpenStreetMap Sweden — Map data © OpenStreetMap' });