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.

Merge branch 'testing' into develop: Examples/python/simulation now covered by functional persistence tests. This resolves much of #1440.

Meaningful persistence tests in place for all Example/python/simulation, except for SpecularSimulation.py which only writes a trivial text line. This resolves much of #1440.

This is, however, no good solution because one test may write several intensity maps with different reproducibility levels.

IntensityDataFunctions::getRelativeDifference has now same implementation for IHistogram and for OutputData<double>.