* rename maxOnOverflow parameter to CoordToRowOrCol() to clipToMinMax

 * rename maxOnOverflow parameter to CoordToRowOrCol() to clipToMinMax

 * ensure CoordToRowOrCol() range is  0 -> nMax if clipOnMinMax is set
                                and -1 -> nMax if clipOnMinMax is not set

 * check on uses of YToRow() / XToCol() and replace with
   calls internalYToRow() / internalXToCol() removing any external
   overflow handling where appropriate.

 * Add tests for overflow to prevent sending 'off grid' label events,
   would be indistinguishable from CornerLabel events.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@19972 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775