add python-compat for obj-to-str

include/dynamic-graph/python/CMakeLists.txt

include/dynamic-graph/python/convert-dg-to-py.hh

include/dynamic-graph/python/dynamic-graph-py.hh

include/dynamic-graph/python/exception-python.hh

include/dynamic-graph/python/interpreter.hh

include/dynamic-graph/python/python-compat.hh

include/dynamic-graph/python/signal-wrapper.hh

src/CMakeLists.txt

src/dynamic_graph/CMakeLists.txt

src/dynamic_graph/convert-dg-to-py.cc

src/dynamic_graph/debug-py.cc

src/dynamic_graph/dynamic-graph-py.cc

src/dynamic_graph/entity-py.cc

src/dynamic_graph/factory-py.cc

src/dynamic_graph/pool-py.cc

src/dynamic_graph/python-compat.cc

src/dynamic_graph/signal-base-py.cc

src/dynamic_graph/signal-caster-py.cc

src/dynamic_graph/signal-wrapper.cc

src/interpreter.cc