Adding normalization option when saving OBJ
changlog and BB reset in clear()
 [-1,1]->[-1/2,1/2]
doc
Fixes
warnings
Warning again
minor fix in Display3D addLine
Merge pull request #820 from dcoeurjo/noramlizedOBJ

Normalized obj
fix travis warning
Merge pull request #824 from kerautret/FixTravis

fix travis warning
Reorg ChangeLog and fix conflict.