TAChart: Add IChartDrawer.PutImage procedure

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40052 4005530d-fff6-0310-9dd1-cebe43e6787f
TAChart: Extract TBasicPo.FindExtentInterval procedure
+ Minor refactoring.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40053 4005530d-fff6-0310-9dd1-cebe43e6787f