Add Basque Language

(empty description)

assigned to @pokoli

added type::feature + 1 deleted label

The language is avaialbe in https://translate.tryton.org/languages/eu/tryton/

added 1 deleted label and removed 1 deleted label

We need a patch which adds the language to ir/lang.xml and update the setup.py like review22171002.
Also it will be good to put translators in copy of this issue (and flag them as translator on bugs.tryton.org).

unassigned @pokoli