Make workboard sort-order inversions more clear by using "-1 * ..." instead of "(int)-(int)"

Summary: Depends on D20279. See D20269. Agreed that explicit `-1` is probably more clear.

Test Plan: Viewed boards in each sort/group order.

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D20281

src/applications/project/order/PhabricatorProjectColumnCreatedOrder.php

@@ -27,8 +27,8 @@ final class PhabricatorProjectColumnCreatedOrder
 
   protected function newSortVectorForObject($object) {
     return array(
-      -(int)$object->getDateCreated(),
-      -(int)$object->getID(),
+      -1 * (int)$object->getDateCreated(),
+      -1 * (int)$object->getID(),
     );
   }
 

src/applications/project/order/PhabricatorProjectColumnPointsOrder.php

@@ -42,8 +42,8 @@ final class PhabricatorProjectColumnPointsOrder
 
     return array(
       $overall_order,
-      -(double)$points,
-      -(int)$object->getID(),
+      -1.0 * (double)$points,
+      -1 * (int)$object->getID(),
     );
   }
 

src/applications/project/order/PhabricatorProjectColumnPriorityOrder.php

@@ -39,7 +39,7 @@ final class PhabricatorProjectColumnPriorityOrder
 
   private function newSortVectorForPriority($priority) {
     return array(
-      -(int)$priority,
+      -1 * (int)$priority,
     );
   }