Add a parameter summary to the output we track doing optimization

[kasperdanielhansen]

Add the output of something like
norm(factor_matrix)
or some other summary of the parameter vector to the printed output. It also makes sense to add a flag which enables or disables the printed output.

In R I tend to use a verbose which can either be a integer (higher values is more verbose) or just true/false, so both
verbose = 5
verbose = TRUE
works.