Features
- Added freeze and unfreeze the matrix option by using `f`
- Added option to change the background color by using ctrl + `r, t, y, u, i, o, p, [` or
by using command line option --background [color]. Colors: red, green, blue, cyan, yellow, magenta and white.
- Added option to change the direction of the matrix to scroll up. Use `v` to toggle scrolling up or -v --reverse from the command line.
Improvements
- Added color black to the matrix letters