Namespace Hack, CLASSES Config Option

This first commit implements the proposed solution B for the Namespace Hack, Part 2 issue:  https://github.com/daoswald/Inline-CPP/issues/7

Included in this commit is the code required to implement the solution, test it in the exact manner shown for the previously-existing t/namespace tests, and document it in the POD file.

There is no code included in this commit that is not directly related to, and required by, the proposed solution B.