Use overlays for candidate display

[clemera]

The function minibuffer-contents is often used to retrieve the current user input. As Selectrum inserts the candidates into the minibuffer they are included which is often unexpected. Maybe Selectrum could use overlays to display candidates like icomplete or advice minibuffer-contents to return selectrum--current-input when Selectum is active.

[raxod502]

I think using overlays is the right thing to do. This has been suggested before, although I cannot recall where. Thanks for the report.