Add more corpora

[stephantul]

We currently offer a nice selection of corpora, but don't offer:

• MRC database
• ~Lexique~ DONE
• ~A spanish corpus~ DONE

Adding Lexique would especially be nice because this would give us a Celex-like database for French (e.g. including syllables and frequency counts)

[stephantul]

Most of the SUBTLEX corpora have been added.

[stephantul]

the CELEX word corpora have been added.

[stephantul]

Added Lexique

[stephantul]

Added Buscar Palabras (bpal), giving us a Spanish corpus.