Adding an example of modelling of an electric vehicle offering flexibility when connected to the system (with a corresponding non-regression test). Moreover, minimal values (1e-5) were replaced to zero, to lighten the problem formulation (non-necessary binaries are now multiplied by zero so they don't appear in the .lp file), all non-regression tests passed (with minor modifications : non-exact values due to previous numerical aproximations were corrected from 1e-5 to zero).