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;