Mini map makeover

Restyled mini-map. Added images for the directional arrow. Added logic to draw the connections between squares. Added a .map-cell.visited css rule that is applied to visited map-cells so that the user can see where they have been. Rotated map 90 degrees to make better use of available space.

Also fixed bugs that caused minimap to not center and the sidebar to not be sized and positioned correctly on initial load.