TAChart: Take bad spline parts into account while calculating nearest point

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41779 4005530d-fff6-0310-9dd1-cebe43e6787f
cody: unit deps: mark units with implementation uses

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41780 4005530d-fff6-0310-9dd1-cebe43e6787f