Add height handling to monitors/calibTools.py
add vertical and horizontal eye positions to monitors/calibTools.py
add method to calculate the coordinates of the viewer relative to the monitor
add handling of user-specified units, plus error checking
add aspect ratio calculation to monitors/Monitor
create a projection-handler method in visual/window.py that can be subclasses to change the projection
add eye position and screen height handling to visual/window.py
add perspective handling to visual/Window.py