BezierInterpolation = function(h1, h2) {
            this.c1 = h1;
            this.c2 = h2;
          }
@class Bezier curve interpolation with configurable coefficients. The curve
parameters need to be normalized offsets relative to the start and end values
passed to the {@link #interpolate(float, float, float)} method, but can
exceed the normal 0 .. 1.0 interval. Use symmetrical offsets to create a
symmetrical curve, e.g. this will create a curve with 2 dips reaching the
minimum and maximum values at 25% and 75% of the interval...
@member toxi

@example
<p>
<code>BezierInterpolation b=new BezierInterpolation(3,-3);</code>
</p>

The curve will be a straight line with this configuration:

<p>
<code>BezierInterpolation b=new BezierInterpolation(1f/3,-1f/3);</code>
</p>