whitelist/gen: read VisistedAt for safari

[adamdecaf]

From #187 I don't see a single-table way to get history items and visit times for safari, but there seems to be a join possible between history_items and history_visits.

CREATE TABLE history_items (id INTEGER PRIMARY KEY AUTOINCREMENT,url TEXT NOT NULL UNIQUE,domain_expansion TEXT NULL,visit_count INTEGER NOT NULL,daily_visit_counts BLOB NOT NULL,weekly_visit_counts BLOB NULL,autocomplete_triggers BLOB NULL,should_recompute_derived_visit_counts INTEGER NOT NULL, visit_count_score INTEGER NOT NULL DEFAULT 0);

CREATE TABLE history_visits (id INTEGER PRIMARY KEY AUTOINCREMENT,history_item INTEGER NOT NULL REFERENCES history_items(id) ON DELETE CASCADE,visit_time REAL NOT NULL,title TEXT NULL,load_successful BOOLEAN NOT NULL DEFAULT 1,http_non_get BOOLEAN NOT NULL DEFAULT 0,synthesized BOOLEAN NOT NULL DEFAULT 0,redirect_source INTEGER NULL UNIQUE REFERENCES history_visits(id) ON DELETE CASCADE,redirect_destination INTEGER NULL UNIQUE REFERENCES history_visits(id) ON DELETE CASCADE,origin INTEGER NOT NULL DEFAULT 0,generation INTEGER NOT NULL DEFAULT 0,attributes INTEGER NOT NULL DEFAULT 0,score INTEGER NOT NULL DEFAULT 0);

CREATE INDEX history_visits__last_visit ON history_visits (history_item, visit_time DESC, synthesized ASC);