message: Add a text message for Convolution layer's input channels check
diff: @@ -259,6 +259,9 @@ public:
  }
  int ngroups = inpCn / blobs[0].size[1];
  + if (ngroups == 0 || ngroups * blobs[0].size[1] != inpCn)
  + CV_Error(Error::StsError, format("Number of input channels should "
  + "be multiple of %d but got %d", blobs[0].size[1], inpCn));
  CV_Assert(ngroups > 0 && inpCn % ngroups == 0 && outCn % ngroups == 0);
  int dims[] = {inputs[0][0], outCn, out.height, out.width};
  