Update Spanish translation

[bjorn]

These are updates to the Spanish translations by Francisco Zamorano (Paco_Zamo), pulled from Transifex.

Since a while I'm no longer using Transifex since Weblate provides a nicer way to update translations, but I noticed there was a substantial update to the Spanish translation still waiting on Transifex.

It needs to be checked though. For example:

• It has translated command-line options like --export-map, which should stay as-is (this one is already excluded from this patch)
• It does not always match the case of the original (for example, "Remove %n Object(s)" translated as "Eliminar %n objetos". These are menu items, and I'm not sure if this is the right thing to do in Spanish (previously this translation did match the casing, as can be seen in the diff).

It would be great if a Spanish speaker could help with reviewing this update.