Merge branch 'v2.4' into v2.5

scripts/partial_tempering.sh

@@ -40,6 +40,9 @@ plumed partial_tempering \$scale < processed.top > topol\$i.top
 WARNING: It's not very robust and there might be force-field dependent issues!
 A few tests are strongly suggested.
 
+WARNING: This script only works if the `awk` command in your system corresponds to
+GNU awk. `mawk`, that is the default on Ubuntu 19, does not work correctly.
+
 1. Compare partial_tempering with scale=1.0 to non-scaled force field. E.g.
 grompp -o topol-unscaled.tpr
 grompp -pp