TAChart: Add event OnHintLocation to TDataPointHintTool which knows the size of the hint window (OnHintPosition is deprecated now). Update "financial" demo to show hint window above data points.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@46272 4005530d-fff6-0310-9dd1-cebe43e6787f