[RM-7008] [refactor] CLineModelElementList m_Elements

Created on 2022-01-24 15:07:58 by Didier Vibert. % Done: 0

m_Elements is a vector of shared_ptr to CLineModelElement

the pointer is useless here, it could simply be a vector of CLineModelElement.

The getter (operator[]) can just return the CLineModelElement by ref (may need a cons getter as well).
The setter is the CLineModelElementList::push_back function which is always called with a new CLineModelElement allocation : it can thus be called with a CLineModelElement rvalue ref that can be moved inside.