[cmake] Use API macro mechanism to export classes

[th-skam]

Based on #88
Close #91

[epernod]

Seems good to me. Let's double check with the ci.

[th-skam]

Not sure whether I should export this one:

CollisionAlgorithm/src/CollisionAlgorithm/BaseElement.h

Lines 13 to 14 in d758a81

	template<class ELMT>
	class ElementContainer {

It's an internal container in BaseElement. It is however part of the public API:

CollisionAlgorithm/src/CollisionAlgorithm/BaseElement.h

Lines 48 to 59 in d758a81

	class BaseElement {
	public:
	typedef std::shared_ptr<BaseElement> SPtr;
	virtual const ElementContainer<PointElement> & pointElements() const = 0;//{ return m_pointElements; }
	virtual const ElementContainer<EdgeElement> & edgeElements() const = 0;//{ return m_edgeElements; }
	virtual const ElementContainer<TriangleElement> & triangleElements() const = 0;//{ return m_triangleElements; }
	virtual const ElementContainer<TetrahedronElement> & tetrahedronElements() const = 0;//{ return m_tetrahedronElements; }

We have to export this in such a case right?

[epernod]

Not sure whether I should export this one:

CollisionAlgorithm/src/CollisionAlgorithm/BaseElement.h

Lines 13 to 14 in d758a81

	template<class ELMT>
	class ElementContainer {

It's an internal container in BaseElement. It is however part of the public API:

CollisionAlgorithm/src/CollisionAlgorithm/BaseElement.h

Lines 48 to 59 in d758a81

	class BaseElement {
	public:
	typedef std::shared_ptr<BaseElement> SPtr;
	virtual const ElementContainer<PointElement> & pointElements() const = 0;//{ return m_pointElements; }
	virtual const ElementContainer<EdgeElement> & edgeElements() const = 0;//{ return m_edgeElements; }
	virtual const ElementContainer<TriangleElement> & triangleElements() const = 0;//{ return m_triangleElements; }
	virtual const ElementContainer<TetrahedronElement> & tetrahedronElements() const = 0;//{ return m_tetrahedronElements; }

We have to export this in such a case right?

If you think it should be accessible from outside, for exemple form a thrid party library or plugin, yes you need to add the API macro.

Edit: I didn't see it was a template class. The Macro need to be added to the template instantiation only. Like here:

CollisionAlgorithm/src/CollisionAlgorithm/geometry/EdgeGeometry.cpp

Line 8 in 49cfa60

template class SOFA_COLLISIONALGORITHM_API EdgeGeometry<sofa::defaulttype::Vec3dTypes>;