membed docs missing
When we re-wrote membed to be called from mdrun, we didn't move the documentation for its command-line parameters, which I think are now read in from a file. So that code has been undocumented in 4.6 and 5.0. The former, now-unused source file that contained the docs has been deleted by 86601a237df, but that's why we have version control.
There's nowhere good to re-add such docs (mdrun -h is already too long, so there's only the PDF reference manual, if someone's keen to do it in LaTeX for 5.0), but we can add a section to docs/user-guide pretty easily for 5.1.