Notes on installing Boost 1.84

[Jean-Noël Grad]

Dear users,

It has been brought to our attention by openSUSE maintainers that 
ESPResSo did not properly manage the lifetime of the MPI environment, 
which leads to random fatal crashes at normal program termination.

The lifetime of MPI global variables has changed in Boost 1.84, and we 
are now observing these random crashes very frequently in ESPResSo. All 
ESPResSo releases since 4.0.0 are affected. The bug has been fixed in 
the python branch and will be backported to the upcoming 4.2.2 release 
of ESPResSo. Users of older releases of ESPResSo will have to either 
migrate to 4.2.2, or use containers like Singularity or Docker to build 
and run ESPResSo with an older Boost release.

Boost 1.84 is progressively being deployed to major Linux distributions, 
and is already available to Homebrew users on macOS, where it cannot be 
rolled back to an earlier release due to how the boost-mpi recipe is 
designed.

Best regards,
Jean-Noël Grad