Implements a Portuguese stemming algorithm proposed in the paper A
Stemming Algorithm for the Portuguese Language by Moreira, V. and
Huyck, C.

Galician is an endangered language spoken in northwest region of Spain.
Galician is morphologically similar to Portuguese but phonetics differs
greatly. Due to the morphological similarity between Portuguese and
Galician, Portuguese stemming algorithm can be adopted to stem Galician
texts.

See http://bvg.udc.es/recursos_lingua/stemming.html for stemming rules.