Naive quantisation script generates buggy model if the float model contains slice ops

Identified in v10

When the float model is loaded, the slice dimensions are stored in m_init during the call to loadInternal. However, this is a temporary vector. The actual dimensions are further derived in init, which is not called in the naive quantisation script. Therefore, the integer model copied from the float model has all slice dimensions set to 0. This produces output tensors with dimensions set to zero and the inference fails during operations that use that tensor.

This issue is related to issue 104 in NNVC v10rc