Namespace Hack, CLASSES Config Option

This pull request contains only 1 commit, and implements the proposed solution B for the Namespace Hack, Part 2 issue:  https://github.com/daoswald/Inline-CPP/issues/7

Included in this pull request 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 pull request that is not directly related to, and required by, the proposed solution B.