Here's a comment on the new gretl 2018c release, since the
discussion that led up to it took place off-list.
It's mostly a bug-fix release, initially driven by Jack's noticing a
bug in the (panel-related) pmean() and psd() functions: they would
produce wrong results if only the first observation of each
individual differed from the others (gretl then mistakenly supposing
that the series in question was time-invariant).
To make the release I rolled git back to 2018b status, fixed this
bug, and also cherry-picked some other minor, safe fixes and
enhancements from git master.
That means that master is still ahead of 2018c, the most noteworthy
innovations not in the release being the new internal definition of
"NA" and the replacement of the "install" command by a new