Merge branch 'v2.3' into v2.4

patches/lammps-6Apr13.config

@@ -27,6 +27,12 @@ make no-user-plumed
 Also notice that command "fix plumed" should be used in lammps input
 file *after* the relevant input parameters have been set (e.g. after "timestep" command)
 
+\bug The provided patch does not pass the virial correctly to PLUMED (see https://github.com/plumed/plumed2/issues/377).
+     If you need to perform constant pressure simulations you should download a LAMMPS version newer than November 2018, where the mentioned bug
+     has been fixed, that natively supports PLUMED 2.4.
+     If you need to use LAMMPS with fixed virial with PLUMED 2.3, you can compile LAMMPS with PLUMED 2.4 using runtime binding and then set the variable
+     PLUMED_KERNEL to load PLUMED 2.3.
+
 See also http://lammps.sandia.gov/doc/Section_commands.html for
 further info on processing LAMMPS input, as well as
 this discussion on github: http://github.com/plumed/plumed2/issues/67.