Cleanups

[jeanphilippegg]

No functional changes, just some refactors and removal of unnecessary code.

[jeanphilippegg]

I have made additional cleanups and fixes.

Just a few general comments on programming:

• I have made the signature parameter optional in a few internal functions (I included denote-format-file-name among those). In general, I think optional parameters are less necessary for internal functions. In this case, I think making it non optional simplifies the code.
• I have removed some checks in multiple functions. I think it is not necessary to ensure that a paramater is of given type, particularly for internal functions. I think it makes the code harder to read.

[protesilaos]

Thank you @jeanphilippegg! I noticed you pushed some changes. Please let me know when you are done, so that I proceed to merged this.

[jeanphilippegg]

I have added a few commits. It is ready to be merged!

[protesilaos]

Merged. Thank you!