Tarmak configuration split accross multiple files

[simonswine]

I think we should investigate if it's necessary to have multiple config files of tarmak split into single files.

Problems with the current approach:

• Defaulting is reapplied once we rewrite a tarmak config (e.g. on tarmak init)
• Rebasing issues with git with large single files
• Comparing changes between versions is quite hard within a single file
• Multi level of objects in one file is quite confusing