HanatoK

> The `.colvars.traj` file is already flushed every time a restart is written, but this cannot always be relied upon. Is it possible to implement a flush frequency? PLUMED has...

It looks like I cannot simply disable `colvarsRestartFrequency` if I use `historyfreq` in the ABF section. Any ideas?

> There should be a backup rotation mechanism. When you have more backups than allowed, delete the old ones... Anyway, we have no control over this. > > Maybe we...

> Looking at this, I wonder if we could just switch this flag on for all functional tests. That would be simpler. Honestly I don't know what to do with...

Hi @jhenin and @giacomofiorin ! Should I regenerate the test data without `enableFitGradients no` for all backends in this PR, or in a separate one?

> I would use this PR, for simplicity. You can change the title. OK. I have changed the title and added a list of TODOs.

Is it possible to implement a `debugForces` option similar to `debugGradients`? There should be a way to capture the forces from the atom groups, and compare them with the cvforce...

While commit https://github.com/Colvars/colvars/pull/887/commits/8cc8ef9c65fa37820e8bf3130e059fc3af948896 seems to fix the problem, in local testing I still get a crash from `003_reinitatoms` since `atoms_map` is not correctly re-initialized after `cv reset`.

Commit https://github.com/Colvars/colvars/pull/887/commits/8cc8ef9c65fa37820e8bf3130e059fc3af948896 should have solved the crash in https://github.com/Colvars/colvars/pull/891. As I have said, while the crash doesn't appear anymore on Github CI, I still get another crash in my local...

> Commit [8cc8ef9](https://github.com/Colvars/colvars/commit/8cc8ef9c65fa37820e8bf3130e059fc3af948896) should have solved the crash in #891. As I have said, while the crash doesn't appear anymore on Github CI, I still get another crash in my...