IM::Engine changes

0.04  2009-08-10
    HTML::TreeBuilder is required for HTML tests

0.03  2009-08-09
    each_plugin's API has changed to be callback based
    plugin_collect HasPlugins method
    Give IM::Engine::User new_with_traits
    PluggableConstructor role for new_with_plugins that let plugins interact
        with User and Message construction
    CLI's run method takes an argument, useful for tests
    guessing-game example of Dispatcher and State
    post_initialization method for plugins
    RequiresPlugins role for plugins that require other plugins
    More documentation

0.02  2009-08-08
    Document most of the user-visible classes
    Use Data::OptList to massage plugin arguments

0.01  2009-07-25
    First version