Needles: Extensions

[nsmela]

implement a slider to extend a needle channel's last point:

• extend a set distance from the last point's coordinates by following the last and the 2nd last points
• drop the new position some distance to create a curve
• generate a bezier curve to make a clean curve
• the distance downsward will and away from the last point will determine the curve's angle and rotation curve

[nsmela]

Progress made. If we want to affect the curve radius of the channels, we need to play with with this offset distance for both the centre curve point and the last curve point.

[nsmela]

Issue retired: if needles need to be adjusted, it should be done in the treatment planning software