Overflow bug in boolean tensor views

[romeric]

The following example illustrates the issue

constexpr seq sall = seq(0,-1,1);
Tensor<float,4,4> a; a.iota(5);
Tensor<bool,4,4> ba5;
ba5(sall,sall) = a == a;

This is because in operator=(const AbstractTensor<Derived,2> &a) of the tensor view the eval from the right hand size expression generates a boolean simd vector of 4 (under SSE) SIMDVector<boo,simd_abi::fixed<4>> but the simd vector of the left hand side (the view itself) is constructed at the time of construction of the view when the incoming rhs is not known of course and this is SIMDVector<bool,simd_abi::scalar>. As a result the loop calls the rhs 4x4=16 times (in a scalar) fashion and rhs as a result being a SIMDVector<boo,simd_abi::fixed<4>> accesses 4 items ahead and hence the memory is accessed beyond it's bounds.

To be consistent we need to implemented the same strategy as its implemented in Tensor constructors that is

FASTOR_IF_CONSTEXPR(is_boolean_expression_v<Derived>) { 
    // do sequential access
}

Of course till SIMDMask is implemented.

[romeric]

Fixed here a05e4a0 for all views excluding random views I guess. Fiter and Diag views don't use vectorisation.

[romeric]

This temporarily fixes the issue so closing for now till #54 is implemented.