[OSAB] Task 2: Allow users to pass titles for the x- and y-axes

[robert]

This is one way to solve Task 2 in https://robertheaton.com/2019/04/14/open-source-for-advanced-beginners-1-bashplotlib/ .

Test:

I ran:

from bashplotlib.scatterplot import plot_scatter

x_coords = [-10,20,30]
y_coords = [-10,20,30]
width = 10
char = 'x'
color = 'default'
title = 'Test Title'

plot_scatter(
    None,
    x_coords,
    y_coords,
    width,
    char,
    color,
    title,
    xtitle="My X Axis",
    ytitle="My Y Axis")

and got:

[robert]

I assigned these scales to variables because we were calling the get_scale function a lot and it was getting a bit messy.