Add list example

[vindarel]

Hello,

little contribution, even if:

I don't understand why but the dialog seems needed. Otherwise no UI shows and I can't C-c C-c the hanged process. Both map and show seem needed too.

The doc speaks about type 2 to have a multiselection list, but :type is not an accepted argument to iup:list.

[lispnik]

@vindarel IupList and IupListDialog are actually two different things. This makes it confusing and is why you didn't find a type attribute on IupList. The *Dialogs in the IUP documentation are like helpers for getting quick input from the user. Most of the IUP dialogs in IUP have a "class", and so can be introspected by the Lisp IUP bindings. Unfortunately, IupListDialog doesn't follow that pattern. I'll either have a go at wrapping the IupLispDialog, or document it as not covered by the bindings.

[vindarel]

Ah, thanks. Now :multiple is the keyword.