Language codes: Use proper standards

[bellaPatricia]

The currently used standard is non existend.
Spanisch exists. Latin Spanisch is hacked now with es-la.

Better to use a standard like ISO 639-3.

[bellaPatricia]

Fixed all (except for es-la) in commit c7dfcdf

Waiting for proper translation of missing lines in Spanish.
Also need to know what dialect this is.