Overhauled export, and other minor updates

modules/invoice/classes/Model/Invoice/Item.php

@@ -84,6 +84,19 @@ class Model_Invoice_Item extends ORM_OSB {
 		return Currency::round($result);
 	}
 
+	public function tax_items() {
+		$result = array();
+
+		foreach ($this->invoice_item_tax->find_all() as $iit) {
+			if (! isset($result[$iit->tax_id]))
+				$result[$iit->tax_id] = 0;
+
+			$result[$iit->tax_id] += $iit->amount;
+		}
+
+		return $result;
+	}
+
 	// This total of this item before discounts and taxes
 	public function subtotal() {
 		return Currency::round($this->price_base*$this->quantity);