Add global settings wipe

src/net/apocalypselabs/symat/Interpreter.java

@@ -395,7 +395,7 @@ public class Interpreter extends javax.swing.JInternalFrame {
             try {
                 FileUtils.saveFile(commandsForExport,
                         FileUtils.getFileWithExtension(fc).toString(),
-                        false);
+                        true);
             } catch (IOException ex) {
                 JOptionPane.showInternalMessageDialog(this,
                         "Error saving: " + ex.getMessage(),

src/net/apocalypselabs/symat/PrefStorage.java

@@ -89,6 +89,15 @@ public class PrefStorage {
         return true;
     }
 
+    /**
+     * Wipe all settings.
+     *
+     * @throws java.util.prefs.BackingStoreException
+     */
+    public static void wipe() throws BackingStoreException {
+        prefs.clear();
+    }
+
     // xkcd 221 compliance.
     int getRandomNumber() {
         return 4; // chosen by fair dice roll.