Grids:
- propagate CellHint to Application.Hint, so it can be used in Application.OnHint
- fix displaying CellHint if this has a "long hint".
Fixes issue #0026957.


git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@46760 4005530d-fff6-0310-9dd1-cebe43e6787f