Wrap setAliases() in Platform.runLater() (#885)

Fixes issue #884 (see issue for more info).

AliasItemEditor.save() modifies objects that are observed by the
TableView's underlying SortedList.  Thus, the TableView's selection can
change by calling save(), which means the ListChangeListener can be
fired.

This is a problem for two reasons.
1. The alert dialogue that prompts the user to save a modified alias
will show when the user presses the "save" button, because saving
modifies the selected alias and causes the list to update.

2. setAliases() calls Alert.showAndWait().  From the JavaDoc:
"It must not be called during animation or layout processing."
This statement is likely there because it can cause issues like the one
here: TableView's layout processing (and the list updating) is paused
and the list is further modified (by calling save()).  Thus, when the
processing is resumed the list is in a different and unexpected state.

Calling setAliases() from Platform.runLater() will allow the SortedList,
TableView, and any other involved objects to finish processing changes
before more modifications are made.  Additionally, it allows save(),
when called by pressing the save button, to complete and set the
modifiedProperty to false, so setAliases() does not display an
additional save prompt.

src/main/java/io/github/dsheirer/gui/playlist/alias/AliasConfigurationEditor.java

@@ -422,7 +422,7 @@ public class AliasConfigurationEditor extends SplitPane
             mAliasTableView.setItems(getAliasSortedList());
             mAliasTableView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
             mAliasTableView.getSelectionModel().getSelectedItems().addListener((ListChangeListener<Alias>)c -> {
-                setAliases(mAliasTableView.getSelectionModel().getSelectedItems());
+                Platform.runLater(() -> setAliases(mAliasTableView.getSelectionModel().getSelectedItems()));
             });
         }