[Structural] Adding "use_old_stiffness_in_first_iteration" to the GUI and false by default

[AlejandroCornejo]

@RiccardoRossi @rubenzorrilla @loumalouomega

As we know, in non-linear simulations in solids is mandatory to add always the "use_old_stiffness_in_first_iteration" to be true in the json in order to properly work.

In this PR I am adding this line an setting it to true always. De we agree on this?

Regards

[rubenzorrilla]

By doing it in this way you'll be setting it to true also in linear simulations. Besides, you're not exposing it to the GUI.

Instead, I'd expose this parameter in the GUI, making it active if a non-linear analysis is selected. You can default it to true in there.

[AlejandroCornejo]

Now the parameter is set only in non_linear simulations. IMO, in non linear constitutive problems always should be true so I would not expose it to the GUI. If we need to expose it I'd need the help of @jginternational to do that :)

[rubenzorrilla]

Now the parameter is set only in non_linear simulations. IMO, in non linear constitutive problems always should be true so I would not expose it to the GUI. If we need to expose it I'd need the help of @jginternational to do that :)

I think it must be exposed. Note that it has an extra computational cost, which might be not always required. You can default it to true. I don't think it is a good idea to hardcode it like this. If you want to hardcode things, the GiD GUI scripts is not the place as you will be only hardcoding for the GiD users. The place is the solver defaults.

[jginternational]

I'd recommend the changes above so the parameter is shown in gui

[AlejandroCornejo]

Now it is exposed to the GUI but set false by default.

[AlejandroCornejo]

I think now should be fine right @rubenzorrilla ?

[rubenzorrilla]

I think now should be fine right @rubenzorrilla ?

It is. Thanks!