Added PrependColumn methods and short cuts. Added test for DeleteColumn to sample

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@49233 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/datavgen.cpp

@@ -3759,6 +3759,16 @@ bool wxDataViewCtrl::AppendColumn( wxDataViewColumn *col )
     return true;
 }
 
+bool wxDataViewCtrl::PrependColumn( wxDataViewColumn *col )
+{
+    if (!wxDataViewCtrlBase::PrependColumn(col))
+        return false;
+
+    m_cols.Insert( col );
+    OnColumnChange();
+    return true;
+}
+
 void wxDataViewCtrl::OnColumnChange()
 {
     if (m_headerArea)