Allowing user defined registration to bootstrapper's Spring container

[Former user]

Hi, Great framework, but I was quite limited in using Spring container of the Spring bootstrapper. It creates the container, imports all registrations only from Rtti and builds the container. However I have some prepared registration procedures from other "Spring4D" projects, and basically, explicit registration is from my perspective better IoC than hard-coded attributes. Some registrations (like using DelegateTo and other use of anonymous procedures) are not possible using attributes.

For this reason I have added optional initialization anonymous procedure to be launched before import of registrations from Rtti. See the attached patch. This is my suggestion for the project, comments and corrections are of course welcomed.