Add auto_vacuum to SQLite database installs

[rickc]

SQLite will quickly grow in size as data is added and deleted. Today I ran the VACUUM command on mine. It shrank from 45 megabytes to 52 kilobytes. If the database is created with

PRAGMA auto_vacuum = 1

the will not grow without end because after each commit to the database empty pages are moved to the end of the file and the file is truncated to remove them. The pragma has to be run when the database is created. It has no effect if used after there are tables in the database.

[itrebal]

The SQLite sql_t function supports replacing 'OPTIMIZE TABLE...' to vacuum, but it seems that OPTIMIZE TABLE isn't run very often (ever?) Maybe we should cron-job this.

Rickc, would you write patch for (or at the very least, a new version of) http://trac.habariproject.org/habari/browser/trunk/htdocs/system/schema/sqlite/schema.sql to support it?

[rickc]

OPTIMIZE TABLE/VACUUM is only run on a mass delete of spam, so it isn't run very often. I can write a patch.

[itrebal]

Rick, I meant in particular to have PRAGMA auto_vacuum = 1 set on each table so it does auto-vacuum.

[rickc]

Allow an SQLite installation to run pragmas when the database is created

[rickc]

The attached patch will allow an SQLite installation to run any pragmas when the database is created. A pragma to enable auto_vacuum is added to the SQLite schema file.

[itrebal]

Modified version of the previous fix; dbdelta now runs insert/update queries

[ringmaster]

Applied bug_140.patch in r1396.