Interval

Interval is one of Pablo's display functional units.  It accepts a vector of
input values and represents the data as a set of contiguous bars (either
vertical or horizontal) which span the drawing area and have sizes
proportional to the magnitudes of corresponding scalar values within the
vector.  Each element of the vector having a value greater than 0 is shown
as a bar whose size represents the percentage of the sum of all vector 
elements that the particular element has.

Interval enforces minimum and maximum values which can be set by the user at
configuration time:  Interval treats values it receives outside the acceptable
range as either minimal or maximal, accordingly.


Functional Unit Inputs:  vector

Interval attributes:

	XtNheight   	height (in pixels) of the interval widget
	XtNwidth   	width (in pixels) of the interval widget
	XtNbackground	color of the background of the interval drawing area
	XtNminValue	minimum data value represented by the widget
        XtNmaxValue     maximum data value represented by the widget
	XtNorientation	set to 'horizontal' if the bars are to be stacked
			horizontally and 'vertical' if stacked vertically

