test convolution against explicit reference implementation
test convolution against explicit reference implementation

To thoroughly check convolution, the output is compared against a
reference implementation by explicit looping. Simple and group
convolution by the Caffe and cuDNN engines are checked against the
reference.

gnina/gnina,tackgeun/caffe,gnina/gnina,wangg12/caffe,gnina/gnina,gogartom/caffe-textmaps,tackgeun/caffe,gnina/gnina,wangg12/caffe,wangg12/caffe,gnina/gnina,longjon/caffe,longjon/caffe,CZCV/s-dilation-caffe,gogartom/caffe-textmaps,tackgeun/caffe,CZCV/s-dilation-caffe,CZCV/s-dilation-caffe,longjon/caffe,tackgeun/caffe,wangg12/caffe,gogartom/caffe-textmaps,CZCV/s-dilation-caffe,gogartom/caffe-textmaps,gnina/gnina,longjon/caffe