Eye axes

[gkaguirre]

• The coordinates of the fovea are adjusted for posterior chamber size
• The angle alpha between the visual and optic axes is now derived by reference to the foveal location
• Alpha angle now varies with eye axial length, well replicating Tabernero 2007
• The dilated exit pupil now has a small tilt away from vertical, producing improved fits to the Mathur 2013 obliquity component
• Fixed the contact / spectacle lens routines