add *quiet* kwarg to allow silencing of levenberg_marquardt warnings
add *quiet* kwarg to allow silencing of levenberg_marquardt warnings

matthieugomez/Optim.jl,yuyichao/Optim.jl,JuliaPackageMirrors/Optim.jl,JuliaPackageMirrors/Optim.jl,matthieugomez/Optim.jl,pkofod/Optim.jl,yuyichao/Optim.jl,KristofferC/Optim.jl,KristofferC/Optim.jl,pkofod/Optim.jl,zhmz90/Optim.jl,zhmz90/Optim.jl