Columns input for block_lnlp

[ha0ye]

Output from block_lnlp gives a single character vector for the columns argument, using commas to space out the column indices. This isn't currently an accepted format for input into block_lnlp, which means the user has to do a bit of work to string along multiple runs -- i.e. selecting some sets of columns to run from one output and feeding it into the next run.