Speed up wxDataViewCtrl::SetSelections() on macOS

Don't make many single-item selection adjustments in SetSelections() in
wxOSX and instead implement it with a single native call to
selectRowIndexes:byExtendingSelection:

This has a dramatic, orders of magnitude effect on this call's
performance when selecting many items: selecting 10 thousand items goes
from minutes of runtime and gigabytes of RAM  to unobservable impact in
both.

include/wx/osx/cocoa/dataview.h

@@ -514,6 +514,7 @@ public:
     virtual int  GetSelections(wxDataViewItemArray& sel)   const;
     virtual bool IsSelected(const wxDataViewItem& item) const;
     virtual void Select(const wxDataViewItem& item);
+    virtual void Select(const wxDataViewItemArray& items);
     virtual void SelectAll();
     virtual void Unselect(const wxDataViewItem& item);
     virtual void UnselectAll();

include/wx/osx/core/dataview.h

@@ -90,6 +90,7 @@ public:
   virtual int  GetSelections(wxDataViewItemArray& sel)   const = 0; // returns all selected items in the native control
   virtual bool IsSelected   (wxDataViewItem const& item) const = 0; // checks if the passed item is selected in the native control
   virtual void Select       (wxDataViewItem const& item)       = 0; // selects the passed item in the native control
+  virtual void Select       (wxDataViewItemArray const& items) = 0; // selects the passed items in the native control
   virtual void SelectAll()                                     = 0; // selects all items in the native control
   virtual void Unselect     (wxDataViewItem const& item)       = 0; // unselects the passed item in the native control
   virtual void UnselectAll()                                   = 0; // unselects all items in the native control

src/osx/cocoa/dataview.mm

@@ -2508,6 +2508,20 @@ void wxCocoaDataViewControl::Select(const wxDataViewItem& item)
             byExtendingSelection:GetDataViewCtrl()->HasFlag(wxDV_MULTIPLE) ? YES : NO];
 }
 
+void wxCocoaDataViewControl::Select(const wxDataViewItemArray& items)
+{
+    NSMutableIndexSet *selection = [[NSMutableIndexSet alloc] init];
+
+    for ( const auto& i: items )
+    {
+        if ( i.IsOk() )
+            [selection addIndex:[m_OutlineView rowForItem:[m_DataSource getDataViewItemFromBuffer:i]]];
+    }
+
+    [m_OutlineView selectRowIndexes:selection byExtendingSelection:NO];
+    [selection release];
+}
+
 void wxCocoaDataViewControl::SelectAll()
 {
     [m_OutlineView selectAll:m_OutlineView];

src/osx/dataview_osx.cpp

@@ -648,8 +648,7 @@ void wxDataViewCtrl::SetSelections(wxDataViewItemArray const& sel)
     }
 
     // finally select the items:
-    for (i=0; i<noOfSelections; ++i)
-      dataViewWidgetPtr->Select(sel[i]);
+    dataViewWidgetPtr->Select(sel);
 }
 
 void wxDataViewCtrl::Unselect(wxDataViewItem const& item)