Split plugin start and setup phase.

Split plugin start and setup phase.

Earlier SQLite3 version doesn't provide sqlite3_prepare_v2(), so if
you change the database schema (ie: create another table or trigger,
...) the previously prepared statements are invalidated and need to be
regenerated, sqlite3_prepare_v2() does that for us, but we need not to
rely on that to run on some older platforms (maemo bora).

Plugins now should create tables on setup() and prepare statements on
start().