Create Mesh : Netgen_1d_2d delete and add some parameters in the GUI

Remove the parameter Mesh size pour Netgen 1D-2D in the GUI because it isn't taken into account.

Add the parameter : Growth Rate (facteur d'accroissement des tailles de maille) and put a value by default : 1.3

Do so that the user isn't able to put a value < 1.