Add (some) context menu actions to variable list #290

gb would like "Copy to Excel" in that context menu to avoid having the risk of selecting a single cell when focusing the array widget. In fact, one can use Ctrl-E directly (right after selecting the variable in the list) for an even more efficient workflow. Since it is not obvious at all that this works (and one has to know the keyboard shortcuts), having the context menu on the variable list for all actions which can work on the entire variable (all except paste) would indeed make sense.