Move to libstemmer, add more languages
Replace the in-tree, SQLite-based stemmer with libstemmer, and perform stemming directly via the library rather than via SQLite.
Libstemmer supports more languages than the in-tree stemmer, and supports selecting the stemming language at runtime, not when the last appropriate DB upgrade occurred.
Fixes #334 (closed), see also #147
Edited by Michael Gratton