patchmatch以及patchmatchstereo算法的python版实现
由于patchmatchstereo没有做任何优化，并且是python的代码，主要是方便解析算法的原理构造，适合跑小图，patch_size尽量小一些。
python patchmatchstereo.pypatch_size=5, n_iter=3 结果
| Initialize memory cost 0.002 seconds. | Initialize parameters cost 7.834 seconds. | Initialize gray cost 4.167 seconds. | Initialize gradient cost 2.902 seconds. | Initialize cost 140.518 seconds. | Initialize cost 9.439 seconds. | Propagation iter 0 cost 2033.533 seconds. | Propagation iter 0 cost 1755.244 seconds. | Propagation iter 1 cost 1753.473 seconds. | Propagation iter 1 cost 1764.548 seconds. | Propagation iter 2 cost 1839.081 seconds. | Propagation iter 2 cost 1751.648 seconds. | Propagation cost 10897.527 seconds. | Plane to disparity cost 1.132 seconds. | LR check cost 2.028 seconds. | Fill holes cost 1.012 seconds. | Total match cost 10916.557 seconds. | Get disparity map cost 0.004 seconds. | Get disparity cloud cost 24.264 seconds. 
