Idea: rather than repeat "testing_" in every filename, what if we reorganize the files so that we wouldn't need to:

/ - hosts all quiver.* library headers
/src/ - hosts all implementations of quiver.* libraries
/testing/ - hosts all quiver.testing.* library headers
/testing/src/ - hosts all implementation of quiver.testing.* libraries

In short, we leave / and /src/ directories unchanged, and add a new subdirectory /testing/ that would host all of "testing" code.

Some advantages:
- "testing" code is clearly separated from production code
- shorter file names

What do you think?