Create LICENCE
Creates LICENCE
Merge branch 'master' of https://github.com/NikolaMancic/Snake

Conflicts:
	LICENCE
Refactors tile set addition and selection

-Creates a TileSet class and instances for all current tile sets.
-Simplifies adding new tile sets to game and UI.
Add new UI elements

-Creates a new div for UI elements.
-Adds Title, helpful text and 'continue' and 'back' buttons to new UI div
Enables UI elements and refactored stages

-Adds functionality to 'continue' and 'back' buttons
-The new UI progresses to the next step after the 'continue' button is pressed rather than the stage or tile set icon
-Remembers choices when moving between steps
Fixes random tile set bug