Fix minor stuff (and add dialyxir to CI)

[paulo-ferraz-oliveira]

Some compilation warnings remain, but that's due to what's pull requested next to benchfella, which I wouldn't mind waiting for:

• approval
• + merge
• + tag/release
• + import here

to have the most updated / warning-free code.

[paulo-ferraz-oliveira]

(not sure if the lib. is still maintained). @zyro, bump! 😄 Thanks.

[paulo-ferraz-oliveira]

Close'ing as this doesn't seem to move forward.