Added ppp mobile by porting from netcfg.
Simplify wpa network block creation

It had grown a little diffuse.
Documentation update

Rebuild all the manpages because version information may have changed.

Add a few words on options that are ignored in some cases.
Support more interface types

This allows future connection types to use interfaces other than
networking interfaces, for instance to use USB interfaces.
Code tidying up. Renamed mobile connection to mobile-ppp.

Also:
- Replaced echos with invocations of cat, where possible.
- Fixed PIDFILE to point to the file ppp creates. This ensures the
  interface can be brought down.
- Fixed setting of InterfaceRoot.
- Removed vim syntax highlighting from ethernet connection.