ADDED: Group/Ungroup function

This implements the group/ungroup functions to mark a set of EDA_ITEMs as a unit, allowing them to be moved and rotated as a unit

pcbnew/board_commit.cpp

@@ -220,6 +220,7 @@ void BOARD_COMMIT::Push( const wxString& aMessage, bool aCreateUndoEntry, bool a
                 case PCB_DIMENSION_T:           // a dimension (graphic item)
                 case PCB_TARGET_T:              // a target (graphic item)
                 case PCB_MARKER_T:              // a marker used to show something
+                case PCB_GROUP_T:               // a group of items
                 case PCB_ZONE_AREA_T:
                     view->Remove( boardItem );
 
@@ -424,3 +425,9 @@ void BOARD_COMMIT::Revert()
 
     clear();
 }
+
+bool BOARD_COMMIT::HasRemoveEntry( EDA_ITEM* aItem )
+{
+    COMMIT::COMMIT_LINE* line = findEntry( aItem );
+    return line != nullptr && line->m_type == CHT_REMOVE;
+}