Unified blocklist/imagelist/permissionslist.

Unified blocklist/imagelist/permissionslist.
File format is still under discussion, but the internal changes
are (mostly) done.

Also modified interceptor behaviour:
- We now intercept all URLs beginning with one of the following
  prefixes (and *only* these prefixes):
    * http://i.j.b/
    * http://ijbswa.sf.net/config/
    * http://ijbswa.sourceforge.net/config/
- New interceptors "home page" - go to http://i.j.b/ to see it.
- Internal changes so that intercepted and fast redirect pages
  are not replaced with an image.
- Interceptors now have the option to send a binary page direct
  to the client. (i.e. ijb-send-banner uses this)
- Implemented show-url-info interceptor.  (Which is why I needed
  the above interceptors changes - a typical URL is
  "http://i.j.b/show-url-info?url=www.somesite.com/banner.gif".
  The previous mechanism would not have intercepted that, and
  if it had been intercepted then it then it would have replaced
  it with an image.)