The RA SPP Plugin collection 0.2.2

The RA SPP Plugin collection package provides several plugins meant to be used with a qmail patched using qmail-spp.
They cover diverse areas, and are meant to be written according to the following principles:
- Good performance
They are written whenever possible in C, and try to be short and direct.
- Good logging
They should inform the user of what they do. No email should ever be rejected without logging something. Also, all plugins logs include the PID of the qmail-smtpd process, so you can easily group all events of a connection.
- Security
Since writing in C exposes oneself to the dangers of memory corruption, I have tried to use, whenever it makes sense, the Better String Library, to avoid problems. While this makes the plugins larger, it also makes me feel more comfortable.
Also, for most plugins, it should be possible to run them as a very unprivileged user or in a chroot jail. This is not yet implemented, but it is worth thinking about.
Enhancements:
- Fixes a stupid bug in the ipthrottle plugin (it was sending a debug message to the client).