findByType refactoring

First commit adds findByType method to ContainerBuilder, which is basically a mirror of the method of the same name from Container.

Second commit adds the possibility to return all services of specified type from ContainerBuilder::findByType, as opposed to just autowired ones.

Third commit does the same thing for Container::findByType, but introduces a BC break.

This pull request supersedes https://github.com/nette/di/pull/1