Fix color order in palette file

[stowersjoshua]

Swaps positions of red and magenta color values in palette file.

Based on solution from @j-hap on issue https://github.com/dracula/gnome-terminal/issues/6.

This PR also null terminates the file to conform to POSIX guidelines.

Before:

After:

[stowersjoshua]

Based on https://github.com/dracula/gnome-terminal/commit/4327cd6d69b89e9a21defc2a1276f1e018e77574, this may have been intentional.