Use filter_map

[Masynchin]

Simplify parse_module with using filter_map.

Also, something is trying to update rlci version from 0.1.0 to 1.1.1 in Cargo.lock, I didn't include it in this PR.

[orsinium]

Beautiful! Thank you :)

Also, something is trying to update rlci version from 0.1.0 to 1.1.1 in Cargo.lock, I didn't include it in this PR.

Good catch, thank you. I'll fix it. I didn't know the project version resides in the lockfile as well and didn't actualize lockfile after bumping the version. That should be easy to fix.