#242 key binding for invert selection of file or dir under cursor

[Andras Vinter]

It would be great if we could have a key binding for inverting the selection of a single item at the cursor's location (file or directory).

Also it would be good to have a key binding for "invert selection and move the cursor down by one".

The reason for this is because there are many people with decades of muscle memory on Norton Commander, Total Commander, etc , where you could select/deselect with the space key or with insert key if you also wanted to move down after inverting selection.