Show the colorbar, it will be attached to the last plot.

        Not for the histogram2d, only for the scatter_table.
        Global mlimits should be set for this to properly reflect the
        colormap of each subplot.

        :param label: axis label for the colorbar.
        :param horizontal: boolean, if True the colobar will be horizontal.

def set_colorbar(self, label='', horizontal=False):
        """Show the colorbar, it will be attached to the last plot.

        Not for the histogram2d, only for the scatter_table.
        Global mlimits should be set for this to properly reflect the
        colormap of each subplot.

        :param label: axis label for the colorbar.
        :param horizontal: boolean, if True the colobar will be horizontal.

        """
        if self.limits['mmin'] is None or self.limits['mmax'] is None:
            warnings.warn('Set (only) global point meta limits to ensure the '
                          'colorbar is correct for all subplots.')
        self.colorbar = {'label': label,
                         'horizontal': horizontal}