GSOC: Dependency Injection

I don't know if this is still relevant, but...

When Doug G. and I were at Kona I described the dependency injection
pattern to him and his eyes lit up because he saw it could eliminate
lots of dependency carrying in the Clang codebase
(<http://tutorials.jenkov.com/dependency-injection/dependency-injection-benefits.html>)

We agreed at the time that refactoring things to use DI might make a
great GSOC project. Also, I should mention
https://bitbucket.org/cheez/dicpp, which is like Guice for C++

HTH,