Changes to plugins to allow them to render vertically or horizontally.
Updates to features and documentation, bugfixes

- added a command to Bindings.py to orient the image to North=Up
  - default binding to 'o' creates left-hand orientation, 'O' for right-hand
- added a command to Bindings.py to rotate the image in 90 deg increments
  - default binding to 'e' rotates by 90 deg, 'E' for -90 deg
- fixed a bug in the Tk version where zooming via scroll wheel was broken
- fixed a bug in reference viewer where the Pan widget was updating oddly
    when the main image was rotated and interactive cuts are applied
- documented new commands, added a bit of new documentation
Updated WhatsNew