Improve argument parsing, and allow establishment of route(s) via the new container interface

The parsing of arguments has been improved, adding support for long- and short-form options.

New -v|--verbose option allows pipework to print a play-by-play of argument parsing and what it is doing, to assist in diagnosis when things go unexpectedly.

The new -r|--route <network> option allows specifying one or more new routes in the container using the new interface.  This is useful, for example, to set up multicast to use the new interface, eg. --route 224.0.0.0/4 

Also cleaned up some of the conditionals and variable quoting.