[ptx] Morphing control points

[Jim Watters]

When optimizing this is not quite what is being done.  Currently, each 
pair of T+ points is only compared to the first same T+ points. The 
exception is the first pair is compared to the second pair.  The 
furthest two points set the line and the other two have the error 
calculated.   The difference may be slight in the end.  But this 
approach may improve things.  Needs testing.

Jim

>> For T+ points, modify all the middle points of a set of line points.
>> Use the two furthest points to define the line and modify the points
>> that are in between.  The middle points need to be moved perpendicular
>> to the line.
>
>
> The proper way to handle a straight line is to calculate a best fit 
> (RMS error) line past all the points, and then calculate the error for 
> each point as the perpendicular offset.
>
> I.e. use the same distance for the morphing distance as is already 
> used for the normal error calculation.
>
> Terje