Add column parameter to wxListCtrl::GetItemText().

Allow retrieving the text from columns other than the first one directly.

Add implementations for MSW and generic versions, documentation and a unit
test.

Closes #11597.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@64281 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/listctrl.cpp

@@ -4562,9 +4562,9 @@ wxGenericListCtrl::SetItemColumnImage( long item, long column, int image )
     return true;
 }
 
-wxString wxGenericListCtrl::GetItemText( long item ) const
+wxString wxGenericListCtrl::GetItemText( long item, int col ) const
 {
-    return m_mainWin->GetItemText(item);
+    return m_mainWin->GetItemText(item, col);
 }
 
 void wxGenericListCtrl::SetItemText( long item, const wxString& str )