Support for `i18n`

[fgmacedo]

Description

Add support for internacionalization, translating the exception messages as an example.

[brunolnetto]

I can contribute with german and español. ¿Que tal?

[brunolnetto]

Is there some progress in this direction?

[brunolnetto]

Anybody who will implement this issue requires pointers. The following is instructive: https://docs.python.org/3/library/i18n.html

Since it relies on a normalization refactory, some in-locus implementation guidelines are welcome as well.