relax SVN archive

The n_state_model user function menus now use icons.

Created a set of basic icons for the N-state model user functions.

Improved the PyMOL ray-traced n_state_model wizard graphic by ray-tracing to 1000x1400 and shrinking.

Created a wizard graphic for the n_state_model user functions.

Converted the n_state_model user functions to the auto-generation design.

Some of the documentation was updated as it was incorrect.

The integer user function GUI elements which can be None now are simply set to a wx.TextCtrl.

The wx.SpinCtrl used previously was incorrect, as a wx.SpinCtrl only handles integers, always
defaulting to the minimum of the control. Therefore the can_be_none user function arg arg is now
propagated into the wizard page Value, Sequence and Sequence_2D elements (though they are not
functional in the Sequence* classes yet).

The wx.SpinCtrl used in the Value wizard page element is now fail-safe.

The code now catches min and max values of None, and does not set the initial value so that a
default value of None does not break the wx element!

The min and max args now default to 0 and 1000 for the Uf_container.add_keyarg() method.

This fixes a bug whereby the recently introduced wx.SpinCtrl for the Value wizard page element was
failing as the limits were defaulting to None, which for wx.SpinCtrl is not allowed!

Improved the frame_order relax icons.

Increased the content of icons in the auto-generated user function menus.