Periodic `VACUUM;` to cleanup the client.db file

[Hou5e]

The client.db file size gets somewhat large over time (like 40-80MB for 50-2k WUs). The file size was higher on Windows (where more errors happened). Linux example, 1.5 months of running FAHv8: It could use a periodic SQLite VACUUM; like every 100 WU's, or at startup. After a vacuum, the database file size goes back to about 48-60KB.

[kbernhagen]

Or maybe use PRAGMA auto_vacuum = FULL;