Fix python tools

[victorccampos]

Minor change in "plotband.py"

Currently in plotband.py the image saving is:

if save_png:
        plt.savefig("./band.png")

And this leads to a incomplete band (y-axis):

Adding bbox_inches='tight' prevents this issue:

if save_png:
        plt.savefig("./band.png", bbox_inches="tight")