message: Find sphinx module for documentation generation
diff: @@ -148,6 +148,7 @@ if( PYTHONINTERP_FOUND )
  find_python_module("matplotlib")
  find_python_module("numpy")
  find_python_module("scipy")
  + find_python_module("sphinx")
  endif()
  if(NOT GUDHI_CYTHON_PATH)
  @@ -159,11 +160,15 @@ option(WITH_GUDHI_CYTHON_RUNTIME_LIBRARY_DIRS "Build with setting runtime_librar
  if(PYTHONINTERP_FOUND AND CYTHON_FOUND)
  # Default found version 2
  if(PYTHON_VERSION_MAJOR EQUAL 2)
  + if(SPHINX_FOUND)
  # Documentation generation is available through sphinx
  find_program( SPHINX_PATH sphinx-build )
  + endif(SPHINX_FOUND)
  elseif(PYTHON_VERSION_MAJOR EQUAL 3)
  + if(SPHINX_FOUND)
  # No sphinx-build in Pyton3, just hack it
  set(SPHINX_PATH "${PYTHON_EXECUTABLE}" "${CMAKE_CURRENT_SOURCE_DIR}/${GUDHI_CYTHON_PATH}/doc/python3-sphinx-build.py")
  + endif(SPHINX_FOUND)
  else()
  message(FATAL_ERROR "ERROR: Try to compile the Cython interface. Python version ${PYTHON_VERSION_STRING} is not valid.")
  endif(PYTHON_VERSION_MAJOR EQUAL 2)
  