Given an incomplete genlasso path object, this function continues
the path computation from the last computed knot, either until
the complete path has been computed or the step limit specified by
moresteps has been reached. All options are assumed
to be the same as those in the initial call to a genlasso function (as in
genlasso, fusedlasso, or trendfilter),
with the exception of minlam and verbose, which can be changed
with a call to iterate.