Created by: chengduoZH
fix https://github.com/PaddlePaddle/Paddle/issues/5495 fix https://github.com/PaddlePaddle/Paddle/issues/5507 fix https://github.com/PaddlePaddle/Paddle/issues/5550
- Add dilations for im2col(ColFormat::kCFO).
- Fix conv2d doc (Add dilation)
- Refine conv2d_op unit test.(Add dilation)
- Refine conv_op for filter size:(1,1), (when filter_size, paddings, strides, dilations are (1,1), (0, 0), (1,1), (1,1), conv_op just likes fc_op)
- Add dilations for vol2col(ColFormat::kCFO).
- Fix conv3d doc (Add dilation)
- Refine conv3d_op unit test.(Add dilation)