Merge a bunch of files into one.

The files
- format
- gather
- templates
- output
have now all been merged into `output`.

The difference between `format` and `output` was allways unclear.
`gather` could be separate, but it was still so tightly linked to the
output.

`templates` could have been kept, but it started depending on types from
`output`, making it easier to merge (at least of now).