Rename recurring class filename. Move around some libraries to be under the proper comments.

lib/db.dart

@@ -3,13 +3,13 @@
 // SQLite
 import 'dart:io';
 import 'dart:async';
-import 'package:flutter_expense_tracker/models/recurring_tracked_type.dart';
 import 'package:path/path.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:sqflite/sqflite.dart';
 
 // Local
 import '/models/expense.dart';
+import '/models/tracked_type_recurring.dart';
 
 // Leaned on this example:
 //   https://learnflutterwithme.com/sqlite

lib/models/expense.dart

@@ -1,4 +1,5 @@
-import '/models/recurring_tracked_type.dart';
+// Local
+import '/models/tracked_type_recurring.dart';
 import '/models/frequency.dart';
 
 class Expense extends RecurringTrackedType {

lib/models/income.dart

@@ -1,4 +1,5 @@
-import '/models/recurring_tracked_type.dart';
+// Local
+import '/models/tracked_type_recurring.dart';
 import '/models/frequency.dart';
 
 class Income extends RecurringTrackedType {

lib/pages/expense.dart

@@ -1,12 +1,12 @@
 // Flutter
 import 'package:flutter/material.dart';
-import 'package:flutter_expense_tracker/db.dart';
-import 'package:flutter_expense_tracker/models/recurring_tracked_type.dart';
-import 'package:flutter_expense_tracker/models/tracked_type.dart';
 
 // Local
+import '/models/tracked_type.dart';
+import '/models/tracked_type_recurring.dart';
 import '/models/expense.dart';
 import '/models/frequency.dart';
+import '/db.dart';
 
 // TODO: Make this a generic UI based on a superclass of Expense, Income, and Assets.