LBFGSB still prints messages even with iprint < 0

[bblankrot]

The underlying Fortran code still prints messages regardless of iprint, which clogs up stdout pretty quickly in my case. This could be fixed fairly quickly by adding an if statement to lines 3282-3283 in lbfgsb.f:

write(6,*) ' Positive dir derivative in projection '
write(6,*) ' Using the backtracking step '

If this package uses the C version, the fix is detailed here. I'm not sure how to do it myself since I am unfamiliar with the new dependency-building mechanism.

[Gnimuc]

We can apply this patch to the upstream: https://github.com/JuliaPackaging/Yggdrasil/tree/master/L/L-BFGS-B.

If it's not urgent, I'm going to fix it this weekend.

[bblankrot]

Not urgent at all, thanks a bunch!