TAChart: Add event OnDrawLegend to TChart

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@44583 4005530d-fff6-0310-9dd1-cebe43e6787f
Starts implementing TButtonEdit, a repacement for TEditButton.


git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@44584 4005530d-fff6-0310-9dd1-cebe43e6787f