[CMake] keep the python module as a folder for now

ref
https://github.com/stack-of-tasks/tsid/pull/72#issuecomment-597082552

bindings/python/CMakeLists.txt

@@ -42,6 +42,14 @@ IF(APPLE)
   SET_TARGET_PROPERTIES(${PYWRAP} PROPERTIES SUFFIX ".so")
 ENDIF(APPLE)
 
-SET_TARGET_PROPERTIES(${PYWRAP} PROPERTIES PREFIX "" OUTPUT_NAME ${PROJECT_NAME})
+SET_TARGET_PROPERTIES(${PYWRAP} PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${PROJECT_NAME})
 
-INSTALL(TARGETS ${PYWRAP} EXPORT ${TARGETS_EXPORT_NAME} DESTINATION ${PYTHON_SITELIB})
+INSTALL(TARGETS ${PYWRAP} EXPORT ${TARGETS_EXPORT_NAME} DESTINATION ${PYTHON_SITELIB}/${PROJECT_NAME})
+
+SET(PYTHON_FILES
+  __init__.py
+  )
+
+FOREACH(python ${PYTHON_FILES})
+    PYTHON_INSTALL_ON_SITE(${PROJECT_NAME} ${python})
+ENDFOREACH(python)

bindings/python/module.cpp

@@ -35,7 +35,8 @@
 namespace bp = boost::python;
 using namespace tsid::python;
 
-BOOST_PYTHON_MODULE(tsid) {
+BOOST_PYTHON_MODULE(libtsid_pywrap)
+{
   eigenpy::enableEigenPy();
   eigenpy::exposeAngleAxis();
   eigenpy::exposeQuaternion();

bindings/python/tsid/__init__.py

+from .libtsid_pywrap import *