Improve code quality by addressing Codacity's items

[lupino3]

We enabled a static analysis tool called Codacity, which produces a report with several items that could be fixed.

The report is available here: https://app.codacy.com/project/andrea-spadaccini/edumips64/dashboard

That is a good place to start with contributions: pick some items off that list and fix them! :)

I'd like to keep this issue open as a place-holder, so don't close it but reference it from PRs. Feel free to open more specific issues if deemed useful or necessary.

[pimts]

@lupino3 I'd like to help with fixing some of these Codacy issues. There seem to be quite some Unused Imports issues; 149 at the time of writing this comment. Most of these Unused Imports come from using wildcard imports such as: import org.edumips64.core.*;

What is your stance on wild card imports? Are they allowed in the project or should we explicitly import every class?

[lupino3]

@pimts we didn't really think about this in the past to be honest. It was laziness on our side to use wildcard imports.

I think it's better to avoid them, so please feel free to go ahead and convert them to single-class imports.

Thank you very much for your contribution!