Patch: explain specifically differences of D-BUS to alternatives.

[Havoc Pennington]

Hi,

Thanks, I decided we needed a FAQ anyway and didn't want to clutter the 
tutorial. I edited your text a lot, I guess I'm more comfortable being 
shorter and more noncommittal. I don't want to be getting mails on the 
list about inaccuracies and end up having to maintain some sort of 
comprehensive "which IPC system is right for me" info, I figure we 
should just get people started. Anyhow, FAQ is now online and we
can evolve it over time.

Havoc