[Bf-animsys] Shrinkwrap constraint

[Campbell Barton]

While checking the shrinkwrap constraint I noticed that there is no
way to project -Z direction.

http://www.graphicall.org/ftp/ideasman42/project_z_up_impossible.blend

Suggest 2 options.

- ability to project on negative xyz
- option to use local axis (since its a bit inflexible using global
axis always - you may have objects that rotate together).

I can add these, just mailing for to see if this is OK.

...

also - checked the code and the way that multiple axis get combine
isnt so useful IMHO.

rather then projecting on both X and Z, it will do a single diagonal
projection...
Perhaps it would be better just to select an axis [+X,+Y,+Z,-X,-Y,-Z]

-- 
- Campbell