Add a new helper to handle fiscal issues.

Used initially to provide fiscal year support to the reports.

app/Helpers/FiscalHelperInterface.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace FireflyIII\Helpers;
+
+use Carbon\Carbon;
+
+/**
+ * Interface FiscalHelperInterface
+ *
+ * @package FireflyIII\Helpers
+ */
+interface FiscalHelperInterface
+{
+
+    /**
+     * This method produces a clone of the Carbon date object passed, checks preferences
+     * and calculates the first day of the fiscal year.
+     *
+     * @param Carbon     $start
+     *
+     * @return Carbon date object
+     */
+    public function startOfFiscalYear(Carbon $date);
+
+    /**
+    * This method produces a clone of the Carbon date object passed, checks preferences
+    * and calculates the last day of the fiscal year.
+     *
+     * @param Carbon     $date
+     *
+     * @return Carbon date object
+     */
+    public function endOfFiscalYear(Carbon $start);
+
+}