remove test-related overhead from published examples

We should consider using macros in our examples to achieve the following:

• Don't expose internals (like the reduction of image size for testing) to our users.
• Avoid duplication of source code (currently, examples contain lots of duplicate code).
• When only few lines change from one example to the next, show only those lines to the user.

We would rename all examples from Examples/*/*.py to exSrc/*/*.py.in. The macro processor then writes expanded macros to Examples for user access, and to build/test_output/Examples for automatic testing.