Optionally show more frames in slicer object

[DerkHBos]

Sometimes when modifying the frames in a slicer object it is convenient to have more of them available at a regular distance. Currently, some of them are left out when the path is linear

[arjendeetman]

There is a method that is removing frames if the path is a simple straight line. You can simply disable this method in the predefined slicers.

Adding it as a variable input parameter is also an option. Input parameter 'reduce frames' and have simple strategies for that? Remove from straight lines, remove based on curvature, etc? We can add it as an optional input parameter that can be made visible via de right click menu item.