[For v0.19]Backup files policy

[plgarcia]

Thank you for creating a pull request to contribute to FreeCAD! To ease integration, please confirm the following:

• Branch rebased on latest master git pull --rebase upstream master
• Unit tests confirmed to pass by running ./bin/FreeCAD --run-test 0
• Commit message is well-written
• Commit message includes issue #<id> or fixes #<id> where <id> is the associated MantisBT issue id if one exists

And please remember to update the Wiki with the features added or changed once this PR is merged.

Improvement of saves:

• Handling configuration changes (increasing reducing the number of backups, switching backup, …)
• Changing the naming of the backup with the timestamp instead of numbers.
• Hopefully solves errors on Google Drive.
  See Forum :
  https://forum.freecadweb.org/viewtopic.php?f=8&t=25601

[yorikvanhavre]

This PR is more than one year old and IIRC it was made to respond a google drive problem... Is it still an issue? Should we reconsider merging it? Honestly I'm a bit uneasy with it because it changes a lot of stuff in the file saving system which might potentially bring bugs... So close to the release it might be a bad idea, even more if it's not fixing anything critical. Or we reschedule it for 0.19?

[plgarcia]

The PR proposes also a policy in the naming of the different archives. It also makes the software resilient to file system issues (archive locked for whatever reason, un-ability to erase an archive, ...). these 2   reasons are good enough to take the PR. Google solved the problem obviously, and I did not encounter the problem since many month. But who can ensure other software do not introduce this kind of issues (dropbox, onedrive, anti-virus, ...) It has been tested not only by me, and the change is quite well located in the code. I am updating the PR just in case.   Do whatever you want!

[plgarcia]

I have been rebasing the PR may be 50 times until I gave up. The PR is 1 year and 4 month old.
Now there is a conflict, not complex to sole, I do not understand even why Git does not resolve it by itself.
OK I will solve that conflict, I will rebuild under Windows and retest it, building under linux and retest it also.
I am ready to do that, but my question is is it worth the effort. I think the change is of interest:

• it avoid conflicts with whatever software (Anti virus, ...) would lock an archive and avoid an archive to be deleted (do not tell me it never happens under windows at least)
• it allows to choose the extention of the archives and he name of the archives can be sorted by age.
• if a hardware or software problem occurs FreeCD cannot cope with despite the different measures I put in place, the user is warned (today he does not even know and then may loose his work, do not tell me it does not happen I had the case what is the original reason of this change, the other features being added opportunely)

Tell me if I make this effort the PR will be considered and will not wait an extra 1.5 years until next release, and again and again.

Regards

[wwmayer]

Tell me if I make this effort the PR will be considered and will not wait an extra 1.5 years until next release, and again and again.

No need to put more effort into that. Most of the PR has become obsolete in the meantime anyway and for the part of the PR that can be integrated some refactoring work of FreeCAD must be done beforehand. There I plan to split the code for the backup creation to its own class so that it will be much easier to support different strategies.
But at the moment this is of low priority as I am busy to set-up the new infrastructure for the v0.19 development.

[wwmayer]

Merged.