Make it easier to select feather points close to path points

[TurboGit]

paths: Use SHIFT modifier to select only feather points.

When the border and the feather are very close from each other it is difficult to select a specific point. The default are the border points, when using SHIFT modifier only the feather points are selectable.

Note that for the ellipse the change of the feather mode (equidistant or proportional) is now controlled by the ALT key. This change seems ok as the feature is less frequent and SHIFT is the current key to resize the feather for all masks.