This PR introduces two changes to the declared type signatures:

1. The allowed colors, highlights, and attributes are now checked against defined string literals. This means that, e.g., cprint("hello", "orange") will result in

   error: Argument 2 to "cprint" has incompatible type "Literal['orange']"; expected "Optional[Literal['black', 'grey', 'red', 'green', 'yellow', 'blue', 'magenta', 'cyan', 'light_grey', 'dark_grey', 'light_red', 'light_green', 'light_yellow', 'light_blue', 'light_magenta', 'light_cyan', 'white']]"
   

   when using type checker.
2. The type of first argument of colored and cprint was relaxed to accept objects and not just strings. This makes cprint more in line with print, which accepts arbitrary objects and fixes the example in README which reads

   for i in range(10):
       cprint(i, "magenta", end=" ")

   which currently results in error: Argument 1 to "cprint" has incompatible type "int"; expected "str" when running through mypy.