Visual tweaks with a Window wrapper
First step in implementing player's camera

Only render tiles that are visible within player's FOV.
Keep track of a camera object

Draw every actors, including player that are within the camera's view.
Each turn, if the player's new position is at the edge of the camera,
move the camera so new entities are drawn.
Actual camera width and height

So that the view is not a simple square.
Also clamp the camera to the map dimension, and fixed the problems of
moving around the edge.
Switch back to normal scenes flow and deploy 0.9