Changed interface so that instead of returning other components it hides it behind an abstraction. ie Instead of returning a ProjectBuilder it provides interface to ProjectBuilder. Same with ProjectManager.
This allows interface/implementation to be changed without effecting the "frontend interface" and vastly simplifies writing frontends.
git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@269159 13f79535-47bb-0310-9956-ffa450edef68