Nearly complete lifting card-move code out of workboards

Summary: Ref T10010. This gets rid of the last dependency on the weird ColumnPositionQuery code.

Test Plan:
  - Viewed workboards.
  - Used batch editor.
  - Created a new workboard.
  - Dragged stuff around.
  - Created new tasks into columns.
  - Changed order from natural to priority, dragged things around.
  - Switched filter to custom filter, "all tasks", etc.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10010

Differential Revision: https://secure.phabricator.com/D15176

src/applications/project/engine/PhabricatorBoardLayoutEngine.php

@@ -6,7 +6,7 @@ final class PhabricatorBoardLayoutEngine extends Phobject {
   private $boardPHIDs;
   private $objectPHIDs;
   private $boards;
-  private $columnMap;
+  private $columnMap = array();
   private $objectColumnMap = array();
   private $boardLayout = array();
 
@@ -68,6 +68,17 @@ final class PhabricatorBoardLayoutEngine extends Phobject {
     return $this;
   }
 
+  public function getColumns($board_phid) {
+    $columns = idx($this->boardLayout, $board_phid, array());
+    return array_select_keys($this->columnMap, array_keys($columns));
+  }
+
+  public function getColumnObjectPHIDs($board_phid, $column_phid) {
+    $columns = idx($this->boardLayout, $board_phid, array());
+    $positions = idx($columns, $column_phid, array());
+    return mpull($positions, 'getObjectPHID');
+  }
+
   public function getObjectColumns($board_phid, $object_phid) {
     $board_map = idx($this->objectColumnMap, $board_phid, array());
 
@@ -342,15 +353,16 @@ final class PhabricatorBoardLayoutEngine extends Phobject {
     $board_phid = $board->getPHID();
     $position_groups = mgroup($positions, 'getObjectPHID');
 
+    $layout = array();
     foreach ($columns as $column) {
+      $column_phid = $column->getPHID();
+      $layout[$column_phid] = array();
+
       if ($column->isDefaultColumn()) {
-        $default_phid = $column->getPHID();
-        break;
+        $default_phid = $column_phid;
       }
     }
 
-    $layout = array();
-
     $object_phids = $this->getObjectPHIDs();
     foreach ($object_phids as $object_phid) {
       $positions = idx($position_groups, $object_phid, array());