Add TileLayer and TileLayerFactory

[andyesys]

I have made additions to be able to add tile layers.

• Added TileLayer derived from Layer
• Added TileLayerFactory to create new tile layers
• It is also possible to add inline CSS styling to the map with the new Style Parameter
• Added a method to wait for Map initialization (to wait before adding layers to the map)
• The map create options UrlTileLayer is now optional and if not set, the map is created without a base tile layer

[andyesys]

I am not sure if it is right to merge against the Develop branch. Master is ahead of Develop by 2 commits.