Investigate allowing Pico to support & manage collections of components

This change is dependent on the following, which is much more important.

http://jira.codehaus.org/secure/ViewIssue.jspa?key=PICO-32

There's a lengthy discussion here...

http://lists.codehaus.org/pipermail/picocontainer-dev/2003-July/000640.html.

Its an extension to the idea of Pico supporting multiple implementations where a Map or Collection or Array is available to components themselves - such as custom Registry or Selector components - where Pico instantiates and manages each component in the collection.

This change basically allows for components to interact with collections of other components without having any Pico dependencies. So its a good change to make for generic 'Registry or Selector or Manager' styles of component which need to use and manage collections of components.