Add req.tex file needed to compile the D2.4 document

Signed-off-by: David MENTRE <d.mentre@fr.merce.mee.com>
Add definition of formal methods in D2.4

Signed-off-by: David MENTRE <d.mentre@fr.merce.mee.com>
Add more content on constraints and benefits of formal approaches

Signed-off-by: David MENTRE <d.mentre@fr.merce.mee.com>
Add content about the 3 kinds of formal approaches

Signed-off-by: David MENTRE <d.mentre@fr.merce.mee.com>
Add more example for model checking

Signed-off-by: David MENTRE <d.mentre@fr.merce.mee.com>
Add content for formal approaches for V&V

Signed-off-by: David MENTRE <d.mentre@fr.merce.mee.com>
Update .gitignore to ignore more LaTeX generated files

Signed-off-by: David MENTRE <d.mentre@fr.merce.mee.com>
Add David Mentré as co-author to D2.4

Signed-off-by: David MENTRE <d.mentre@fr.merce.mee.com>
Commit latest PDF for D2.4

Signed-off-by: David MENTRE <d.mentre@fr.merce.mee.com>