Fix examples for leaflet 1.x

[elesdoar]

TODO

• Check markers images not found. PR fix(Markers): fix marker icon broken with latest Leaflet version (1.0) #299
• Mapbox layers in examples

Examples to be fixed:

Basic

• 108 - Changing tiles
• 121 - Toggle between two maps on screen

Layers

• 204 - Dynamic addition/removal of layers
• 210 - HeatMap WebGL overlay example
• 220 - Load a map in non standard projection
• 228 - Esri ArcGIS Clustered Layer
• 229 - Esri ArcGIS Heatmap Layer
• 230 - Yandex layer example
• 230 - Mapbox GL Example

Paths

• 305 - Path change in group layer (MapQuest)

Controls

• 400 - Dynamic addition and deletion of Overlays control

Mixed

• 600 - Image Legend Service