ChangeD2DLayoutAction:
- set initial side view number to 0
- added comment for side view resizing (from previous commit)
D2D5Pane
- removed the THREE_PANE_WIDTH (not used anymore)
- added a ZERO_PANE_WIDTH
- default to 0 views otherwise use the base views for side views
- use the ZERO_PANE_WIDTH when there are zero views