[FEATURE] C file and header for defining printf messages.

[ArielMAJ]

Is your feature request related to a problem? Please describe.
There's too much code and strings in the main file. The code will look more concise and easier to understand and track if the printf messages have their own file implementing them.

Describe the solution you'd like
Create a file with the functions related to test.me's output messages, specially the ones related to #13, #18 and #19 (once implemented for those that aren't already).