Now each unit test subdirectory has an identical copy of main.cpp,
and a file testlist.h that consists of #include's of all other .h
files in the subdirectory.
For the time being, the files testlist.h are not automatically
updated, but there is a script dev-tools/code-tools/update-gtestlist.py
that can be run when needed.

PyPersistenceTest/FitCylindersPrisms_detailed now works.

Restore a few section comments; they are useful even after most details are gone into ad-hoc functions

One more fit example covered by functional tests. BROKEN: unexpected behavior of almost_equal needs to be investigated.

PyPersistTest now compares dat and ref YAML tree entry by entry, allowing for a tolerance for floating-point numbers.
Still to do:
- allow for "VARIABILITY" anywhere in the tree
- generate YAML output from Fit tests.

deprececated exec_programm replaced by execute_process, except in UseLATEX.cmake. Good enough to resolve #1684.

layerwithroughness.py     covered by ex02_LayeredStructures/CorrelatedRoughness.py
detector_resolution.py    covered by ex05_BeamAndDetector/DetectorResolutionFunction.py
cylinders_ba_dwba_size.py covered by ex01_BasicParticles/CylindersInBA.py and CylindersInDWBA.py

Correct decomposition of paths in PyPersistenceTest to allow for directories that contain a dot. This resolves #1583.

correct previous commit; remove last M_PI in our own code (there are still a few in third-party libraries)

Correct .h file header comments: "Declares" -> "Defines". Also remove include comment "inheriting from". This resolves #1550.