Fix: Increased performace

Cache environment, since it doesn't change very often.
Since draw to main canvas when required.
Mod: entity factory location

Moved entity factory to entities folder.
Fix: Monsters not pathing through open doors

Astar map wasn't being updated when the environment changed.
Astar map now updates when the updateEnvironment event is thrown.
Mod: Update readme content
Mod: Coding standard improvements

Multiple suggestions from resharper.
Replaced many array iterations with lo-dash.