This solves #85 in a similar fashion as the color amount detection: the
cursor module now provides a trait that adds a `cursor_pos()` method to
an instance of `Write`. It also corrects that previous implementation
somewhat by making the `CONTROL_SEQUENCE_TIMEOUT` a member of the raw
module and implementing `DetectColors` for any instance of `Write`
rather than just `RawTerminal` (`MouseTerminal` for instance works as
well).

This commit is a major semver bump. Every progra utilizing escape codes generated by Termion is likely broken. The main change is to make each escape has their own type implementing the Display trait.

- Use formatters, mainly Display for escapes.

- Add Truecolor support (`color::Rgb`).

- Put each primitive into distinct modules.

- Add is_tty for checking if some stream is a TTY.

- Add multiple new examples.