This module provides all of the same functionality of WWW::Mechanize, but
adds support for plugins using Module::Pluggable; this means that any
module named WWW::Mechanize::Plugin::whatever... will be found and loaded
when WWW::Mechanize::Pluggable is loaded.

Big deal, you say. Well, it becomes a big deal in conjunction
with WWW::Mechanize::Pluggable's other feature: plugin hooks. When plugins
are loaded, their import() methods can call WWW::Mechanize::Pluggable's
prehook and posthook methods. These methods add callbacks to the plugin
code in WWW::Mechanize::Pluggable's methods. These callbacks can act
before a method or after it, and have to option of short-circuiting the
call to the WWW::Mechanize::Pluggable method altogether.

These methods receive whatever parameters the WWW::Mechanize::Pluggable
methods received, plus a reference to the actvive Mech object.

All other extensions to WWW::Mechanize::Pluggable are handled by the
plugins.