Follow scala file naming conventions

[AlexITC]

We are not following naming conventions on files containing multiple classes.

Expected behavior

Follow file naming conventions from: https://docs.scala-lang.org/style/files.html

Actual behavior

Files containing more than one class should be follow the camelCase style, most files from the models package need to be renamed.

[AlexITC]

It is ok to submit a PR per file change.

[tg44]

Hy!
Can I do a general refactor on the repo?
This "one file one name" thing is a global problem as I saw. (Not just in the models, but in the data dir too; so I assume there are more thing I could rearrange a bit :D )

[AlexITC]

@tg44 Any improvement is welcome.