Fix bug where details view needed a terminal width

The buggy code assumed that, if output isn't to a terminal, then the only view available is the Lines view. This is incorrect, as the Details view doesn't require a set width either, so check for --long even when there's no set width.

src/options.rs

@@ -265,12 +265,26 @@ impl View {
                     TerminalColours::Automatic => Colours::plain(),
                 };
 
+                if matches.opt_present("tree") {
+                    let details = Details {
+                        columns: None,
+                        header: false,
+                        recurse: dir_action.recurse_options(),
+                        filter: filter,
+                        xattr: false,
+                        colours: colours,
+                    };
+
+                    Ok(View::Details(details))
+                }
+                else {
                     let lines = Lines {
                          colours: colours,
                     };
 
                     Ok(View::Lines(lines))
                 }
+            }
         };
 
         if matches.opt_present("long") {