stop-get-current flag on tablist-get-marked-items

[Yuki-Inoue]

I wanted to get the empty list as get-marked-items if non was selected.
So, implemented such option.

[politza]

I think, you can check the result of (tablist-get-marked-items nil t). Items are marked if and only if its length is greater then 2 or its first element equals t.

That seems sufficient, I don't really like to add another option argument to this function.