Update change_color.sh script

[TheBabu]

Right now there are some flaws with the script, but for the major part, it works.

I created this theme using oomox which uses the script from the old upstream. U can see the flaw here is that the textbox color is different from the others.

I've also used the script manually, and I've gotten the same results as the one generated oomox.

I really think that this script has some potential because it allows users who like the arc theme, to change colors to better fit their theme, without having to fork it and maintain their theme separately.

I think the script should have some basic color options that allow a user to create a minimal arc theme, with the more minor details either autogenerated form the base color options a user has provided or uses a color the user has inputted some predefined default color.

Then the script should allow for even more customizability for users who want to configure even the smallest of details. Ideally, the customization options should be in a hierarchy, but depending on how the script works this may or may not work.

I hope users of arc-theme will agree that having such a script is beneficial!

[jonagoldman]

https://github.com/jnsh/arc-theme