Image classification in new C++ core

[wangkuiyi]

Operator list

• momentum_op @sidgoyal78
• fc_op @Xreki
• conv_op @hedaoyuan @typhoonzero
• dropout @xinghai-sun
• batch_norm @jacquesqiao impl batch norm operator #4906
• Relu @QiJune
• pool_op @chengduoZH
• softmax @jacquesqiao @lcy-seso @QiJune
• cross entropy @jacquesqiao @lcy-seso
• accuracy @typhoonzero

Python train file

• implement book/03.image_classification @jacquesqiao
  • VGG-16 issue implement book/03.image_classification train and test #5100 pr 03 image classification #5192
  • ResNet add resnet #5206
  • test acc && fine turn book/03.image_classification Add acc test to image classification #5336

Python inference && accuracy test

• batch_norm test mode