Fortran-like performance (use of "restrict")

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The main difference (or rather the only one?) between Fortran and C is, that Fortran's semantics assumes no pointer aliasing by default (though Fortran as a language allows pointer aliasing) whereas C assumes pointer aliasing is always present.

Pointer aliasing is on of the few major complications almost preventing vectorization and thus the reason why C is so slow and hard to optimize.

To make exceptions to this C semantics rule, restrict appeared in C99. Unfortunately restrict might be quite error prone and thus it's being used mostly in macros or automatically generated code but much less manually. But V generates C, so this is great opportunity for major performance boost in certain use cases and a numerical library should be one of them.

I think to make vnum have excellent performance, restrict will be necessary. See the corresponding V issue proposing using restrict as an important optimization.

Thoughts?