TAChart: Fix drawing of line series with number of points above 1000000

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40043 4005530d-fff6-0310-9dd1-cebe43e6787f
TAChart: Use Split function in data point series editor, see also r39600

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40044 4005530d-fff6-0310-9dd1-cebe43e6787f