italian: Address overstemming of `divano'
italian: Address overstemming of `divano'

Previously 'divano' (sofa) was stemmed to 'div', which is the stem
for 'diva' (diva).  Now it is stemmed to 'divan', which is what its
plural form 'divani' already stemmed to.

Fixes #49, reported by francesco.

snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball