Purity refactor

Purity refactor:

> all math-operators return real array, all math-operators are **pure**
functions.

Why:

+ completely avoid memory leaks;
+ boost performance;
+ parallel-ready.

This change addresses the need by:

+ eliminate all polymorphic, non pure function results.

Side effects:

It could be not fully backward compatible, however it seems quite so.

Add memory leaks workaround

Add memory leaks workaround: fix leaks for convervative and primitive
objects, but not for primitive multispecie one.

Fix bas elemental attribute usage.

Stable release, fully backward compatible.

Add normalize method to cons/prim objects

Add *normalize* method to cons/prim objects: this allows to easy
*normalize* vectorial quantities along a given normal (necessary for
multi-dimensional Riemman Problems).

Stable release, fully backward compatible.

Refactor to be used into FORESEER, stable release, not backward compa…

…tible.

Fields math almost complete, unstable release.

Starting release, not functional.