Fix crash when editing wxDVC items in place in wxOSX/Cocoa.

Fix crash when editing wxDVC items in place in wxOSX/Cocoa.

NSOutlineView::editedColumn: and editedRow: return -1 when they are called
from textDidEndEditing so we need to store their values in textDidBeginEditing
and reuse them later.

This fixes the crash in the sample with out-of-range array index exception
which happened whenever a cell was edited.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62434 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775