Now when doing normal projeciton is possible to ask it to project along the normals
that the vertex would have if it was subsurfaced... this gives "better" projections on
low polys.
Point of this commit is to add the feature request from Eclectiel
http://blenderartists.org/forum/showpost.php?p=1181531&postcount=9
workflow as Eclectiel wanted is now possible:
to archieve a nice low-res retopology that aproximates a high-res mesh when subsurfaced:
1 - make base low-poly retopo
2 - apply a shrinkwrap with projection along normal.. and with SS level = N (where N>0)
3 - add a Subsurface with level N
4 - run bretch's script (ss_fit)