[Core] Proposition to reduce the number of alias declarations

[alxbilger]

The goal is to reduce the number of alias declarations. I propose 2 methods:

1. using traits (for example DataVecCoord_t<Out>). This is illustrated in Multi2Mapping.
2. using a set of macros. The aliases are still declared, but it is hidden inside the macro.

I find the trait approach elegant (nothing is hidden and no use of macro or additional code), but too much verbose when only one template parameter is available (e.g. TetrahedronFEMForceField).

The advantage of the macro is that it does not require changes in the code other than the alias declarations.

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Reviewers will merge this pull-request only if

• it builds with SUCCESS for all platforms on the CI.
• it does not generate new warnings.
• it does not generate new unit test failures.
• it does not generate new scene test failures.
• it does not break API compatibility.
• it is more than 1 week old (or has fast-merge label).

[alxbilger]

[ci-build][with-all-tests]

[damienmarchal]

Mixing real precision in our codebase has the only consequence of making it very harde to track the preservation of a given level of precision (i.e, there is no undesired/un-expected loss).
In previously merged PR related to refactoring/removal of alias declaration the idea was to simply use SReal. So we are compiling SOFA either in double or in float and not a giant mic-mac.

[damienmarchal]

Suggested change

	, d_poisson(initData(&d_poisson, Real_t<DataTypes>(0.3), "poissonRatio", "Poisson ratio in Hooke's law"))
	, d_young(initData(&d_young, Real_t<DataTypes>(1000.), "youngModulus", "Young modulus in Hooke's law"))
	, d_thickness(initData(&d_thickness, Real_t<DataTypes>(1.), "thickness", "Thickness of the elements"))
	, d_poisson(initData(&d_poisson, SReal(0.3), "poissonRatio", "Poisson ratio in Hooke's law"))
	, d_young(initData(&d_young, SReal(1000.), "youngModulus", "Young modulus in Hooke's law"))
	, d_thickness(initData(&d_thickness, SReal(1.), "thickness", "Thickness of the elements"))

[damienmarchal]

Suggested change

	Data<Real_t<DataTypes>> d_poisson; ///< Poisson ratio in Hooke's law
	Data<Real_t<DataTypes>> d_young; ///< Young modulus in Hooke's law
	Data<Real_t<DataTypes>> d_thickness; ///< Thickness of the elements
	Data<SReal> d_poisson; ///< Poisson ratio in Hooke's law
	Data<SReal> d_young; ///< Young modulus in Hooke's law
	Data<SReal> d_thickness; ///< Thickness of the elements

[damienmarchal]

Suggested change

	Real_t<DataTypes> getPoisson() { return d_poisson.getValue(); }
	void setPoisson(Real_t<DataTypes> val);
	Real_t<DataTypes> getYoung() { return d_young.getValue(); }
	void setYoung(Real_t<DataTypes> val);
	SReal getPoisson() { return d_poisson.getValue(); }
	void setPoisson(SReal val);
	SReal getYoung() { return d_young.getValue(); }
	void setYoung(SReal val);

[damienmarchal]

Suggested change

	virtual void applyStiffness(VecCoord_t<DataTypes>& f, Real_t<DataTypes> h, const VecCoord_t<DataTypes>& x, const Real_t<DataTypes>& kFactor);
	virtual void applyStiffness(VecCoord_t<DataTypes>& f, SReal h, const VecCoord_t<DataTypes>& x, const SReal& kFactor);