Update in CMake machinery for new Python_FOUND variable style

Core/CMakeLists.txt

Fit/CMakeLists.txt

Tests/Functional/Python/PyCore/CMakeLists.txt

Tests/Functional/Python/PyEmbedded/CMakeLists.txt

Tests/Functional/Python/PyEmbedded/TestCases.cpp

Tests/Functional/Python/PyExamples/CMakeLists.txt

Tests/Functional/Python/PyFit/CMakeLists.txt

Tests/Functional/Python/PyPersistence/CMakeLists.txt

cmake/bornagain/modules/CPackApple.cmake

cmake/bornagain/modules/CPackWindows.cmake

cmake/bornagain/modules/CheckCode.cmake

cmake/bornagain/modules/FixAppleBundle.cmake.in

cmake/bornagain/modules/GeneratePythonDocs.cmake

cmake/bornagain/modules/PyExamplesLineLength.cmake

cmake/bornagain/scripts/BABuild.h.in