#12 modular feature framework

[Stuart D. Gathman]

Use framework like urllib2 or apache mods to break the
milter application features into smaller dynamically
loaded modules. For instance, spf_mod, dspam_mod,
defang_mod, wiretap_mod. The framework will handle
basic stuff like assigning connection sequence #,
logging, collecting connect_ip and classifying
connections as INTERNAL/EXTERNAL/TRUSTED. Modules will
have handlers for milter events. Modules loading will
be controlled by section names in config file.