Set x-axis limits of a subplot.

        :param row,column: specify the subplot.
        :param min: minimal axis value
        :param max: maximum axis value

def set_xlimits(self, row, column, min=None, max=None):
        """Set x-axis limits of a subplot.

        :param row,column: specify the subplot.
        :param min: minimal axis value
        :param max: maximum axis value

        """
        subplot = self.get_subplot_at(row, column)
        subplot.set_xlimits(min, max)