Made vector_of use primtiiv_of to generate its result.

This make vector_of<logical> not require to be specialized anymore
and open design space for similar vectorizable type in the future.
Fix native model_of to use vector_of

Some architectural with asymmetrical support for vectorized types
requires all mdoel_of based meta-functions to keep generating
correct types even if said generation should lead to an unsupported
base scaalr type. By making native model_of regenerate types using
vector_of, we ensure that unsupported type generate an emulated
native and not cause static asserts.
Made downgrade behavior correct on some more cases
Some more native documentation
fast_rec cover and exhaustive tests