nabu-config: propose templates per beamlines

When reconstructing a lot of datasets sharing common parameters, it is cumbersome to edit configuration file by hand.

Templates

To ease the process, we could propose beamline-specific templates: something like nabu-config --template id19-september-run. Templates could be created by user and stored in a directory (ex. ~/.config/nabu/templates, or --templates-directory).

Multiple config files generator

We could also think of a "config file generator" which would create many configuration files.
Suppose we have many scans sharing the same directory layout:

/path/to/scan/directory
`- scan0001
`- scan0002
`- scan0003
`- ....

Then a convenient tool would be something like nabu-config-many --template <template> --location /path/to/scan/directory --prefix scan --output_location /path/to/reconstructions. The configuration file would be generated in each scanXXXX folder, and the reconstructions set in each corresponding folder.