TAChart: Add IChartDrawer.SetMonochromeColor procedure

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40049 4005530d-fff6-0310-9dd1-cebe43e6787f
TAChart: Add initial support for shadows

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40050 4005530d-fff6-0310-9dd1-cebe43e6787f