message: Now the cython compilation is run before installation on TravisCI.
diff: # Development dependencies
  pip install -r devrequirements.txt
  -pip install .
  # Compile CMBTR extension with cython. The .so file is not generated, as it
  # will be compiled during package setup
  cythonize dscribe/libmbtr/cmbtrwrapper.pyx
  -# TODO: Compile documentation with Sphinx
  +pip install .
  