IOTstack Backup and Restore

This is a fork from IOTstackBackup from Paraphraser. He did the main work and I am thankful for his work.
I have added a way to safe backups on dropbox and to keep a certain number of backups on the raspberry.
I use a Raspi4 with an USB SSD so I have plenty of local space.
I am not an expert with linux nor bash programming. Some lines and ideas are from other sources like dropbox Uploader.

I completely abandoned the idea to use Dropbox because it quickly gets full and asks for a payed upgrade.
Now I do a backup on raspberry and fetch the files from my local PC. I use fetch because the local PC is not always on. I use a windows task to wake up the PC and execute the fetch with scp batch. The task is set to a time where the PC is normally on so it will not wake it up especially for this task.
To implement this I altered iotstack_backup which is now temporaryly in a work state.

If you want to use encryption you have to set up gpg first. You can write the passphrase into a file so it will not ask.
If you do not want encryption simply delete the line with gpg -c --passphrase-file /home/pi/user/pass --pinentry-mode loopback $RUNTAG.FullBackup.tar

The structure of backup folders is:

IOTSTACK-backups
- archive (used temporarily as source for upload)
- archive_old n backups configurable in script
- influxdb influxdb backup merged (tar) into "backup".tar (will be deleted after backup complete)