integrated clang-format

integration/test_classes.py

src/pystencilssfg/configuration.py

src/pystencilssfg/emitters/clang_format.py

src/pystencilssfg/emitters/class_declaration.py

src/pystencilssfg/emitters/header_source_pair.py

src/pystencilssfg/emitters/jinja_filters.py

test_classses_out/test_classes.cpp

test_classses_out/test_classes.h