Changed tkinter to lowercase as capitalised T seemed to be causing problems
Added tkinter key bindings for arrow keys to increment x and y offsets for the grid
Passed offsets to draw functions, but have not used them in grid calculations yet
Implemented arrow-key scrolling as functionality of Map class
Recapitalised Tkinter import (Do not know why my laptop demanded lowercase)
Using canvas move functions, first rectangle of grid can be moved by keys (obeying toroidal plane) but others do not
Fixed resetting of xOffset and yOffset so it occurs after all rects have been shifted. Scrolling is now applied to all tiles.
Bug exists whereby scrolling can cause an empty edge row or col at some point
Large map scrolling is still slow
Scrolling works, holding shift takes larger steps
Shadows can be drawn (darkening colour choices) based on xOccluderDir and yOccluderDir directions to lightsource
Shadowing contributed to most by occlusions in direction of light source, by orthogonal occluders also contribute
Closer occluders contribute more shadow