2. Add crop layer unitest
3. Fix bugs

1. change configure content to 'axis, offset, shape'
2. add an optional input to crop layer as cropping reference

1. change configure content to 'axis, offset, shape'
2. add an optional input to crop layer as cropping reference

Add the use_nnpack parameter in ExpandConvLayer, so that the convolution calculation can be switched to the NNPACK function.

Change the CpuMatrix::copyFrom and CpuVector::copyFrom with the stream parameter to the synchronous interface.

1. v2.layer.parse_network does not correctly handle the generation output.
2. GatherAgentLayer does not correctly handle generation output when batch_size > 1
3. Fix CustomStackTrace for rnn group