Discretization of continuous intervals

• grid_Cons_Equi: Discretizes an interval into equidistant nodes
• grid_Val_Equi: Returns a specific equidistant node of the discretized set
• grid_Inv_Equi: Inverts the equidistant interval nodes to the interval [0, n]
• grid_Cons_Cheb: Discretizes an interval into Chebychev nodes
• grid_Val_Cheb: Returns a specific Chebychev node of the discretized set
• grid_Inv_Cheb: Inverts the Chebychev interval nodes to the interval [0, n]
• grid_Cons_Grow: Discretizes an interval into nodes of growing distance
• grid_Val_Grow: Returns a specific node of the growing distance discretized set
• grid_Inv_Grow: Inverts the growing distance interval nodes to the interval [0, n]