I am trying to use boost::multi_array and want to create a view where I am
lowering the number of dimensions, but I wish the dimension to be reduced
to be decided at runtime.I have a vector of integers and this vector size is the same as the number
of dimensions. If the vector [1] value is -1, then the first dimension
will have all values (i.e. range ()), otherwise it will be a number
indicating what slice to use.