- LabelPlacer
=============
http://citeseer.nj.nec.com/christensen94placing.html
http://citeseer.nj.nec.com/christensen95empirical.html
http://citeseer.nj.nec.com/49900.html
http://www.cs.umd.edu/hcil/excentric/
-1 implements SA algorithm
-2 look up line label placing