Recommendation is to avoid using the year nomenclature as this
information is already encoded in the git repo. Avoids needing to
repeatly update.
Also updates AUTHORS.txt from current repo with contributor names
Instead of the mouse pan and drag algorithms calculating the new
position or rotation values relative to a starting value, the new values
are calculated relative to the current values. This allows the user to
use a second input device to move or rotate the view at the same time
without its change being undone by the mouse.
