Customizable funnel with handle

A parametrizable funnel.
I needed a small one for my own needs, so I share it as it could also be usefull for you.

The OpenSCAD script allows the following parameters:
- Overall thickness (neck tip is thinner than the funnel body and handle).
- Funnel body : height, min and max diameter.
- Funnel neck height and diameter.
- Handle diameter.

The provided STL uses the following parameter values (in mm):
- thickness=1.6; // Overall thickness (neck tip is thinner than the funnel body and handle).
- diam_body_max=50; // Funnel body max diameter
- diam_body_min=10; // Funnel body min diameter
- body_height=25; // Funnel body height (without neck)
- neck_height=20; // Funnel neck height
- diam_neck=6; // Neck tip diameter.
- handle_diam=15; // Handle diameter. If equals 0 => no handle.