Environmental preparation (provide reference)

[Luh1124]

I encountered some problems in the process of environment configuration. The solutions are as follows:

1. BFM

cd examples/Data/BFM and View "readme.md", download files and create the corresponding folder.
You can also follow #95 , according to examples/data/generate.m put the file in the corresponding folder.

2. Cython

pip install cython
cd ./engineer/render/face3d/mesh/cython
python3 setup.py build_ext --inplace
python3 setup.py install