Adds Australia Map coloring problem

[Rishav159]

This commit:

• Adds a map coloring problem with a map of Australia. The states can be colored by choosing a color from a palette and then clicking on the state. The reader is asked to color all the states following the condition that no two neighboring states can have the same color.
• Increases width of the content div in index.html of Chapter 4. This makes the content more clear.
  Development in 6-Constraint Satisfaction Problems #88

[redblobgames]

Nice diagram! The code for drawText, bindClicks would be cleaner if you made a list of areas like

let territories = [
    ['#NT', 'NT', 1/7.5, 1/6],
    ['#WA', 'WA', 1/16, 1/4],
   …
]

That way you can loop through them. Similarly, drawPalette would be simpler if you had a list of colors in the palette.

[redblobgames]

Color suggestions: try changing hsl(,100%,50%) for the main map areas to hsl(,50%,80%). It will make the text easier to read.

For the text, right now it's inheriting the stroke and fill colors from the parent <g>. I suggest stroke:none;fill:black on them to make them solid.

[Rishav159]

Updated as per reviews. However, I am not so sure about the color suggestion.
I have updated from hsl(,100%,50%) to hsl(,80%,70%)
Here is a comparison:
This is with hsl(,80%,70%)

This is with hsl(,50%,80%)

After fixing the text colors, I think hsl(___,80%,70%) looks better. I have updated with the new colors. What do you think ?

[redblobgames]

Looks good! The text is readable now :)