中文说明：实现了基本的基于pca的人脸识别，里面包含训练过程和识别过程，可输出识别率。可读取一张图片，并判断是人脸库中的哪一张。
English Description：
Implements basic face recognition based on PCA, which contains training procedures and identification process, capable of output rate. A picture can be read, and judge which one in the face.