Some minor adjustments

[rcarlsson]

This could be a breaking change depending on how this library is used, but I still think these changes make it more usable, and should be easy to adjust for as a user if needed (just don't call input_byte when receiving line feed if you still want the old behaviour).

As for the change regarding the output "song and dance", I'm not sure if I'm missing something, or if it's just overly complicated. Also the old solution does not work well with terminals like Cutecom, which ignore carriage return.

[rcarlsson]

This should also fix #7

[thejpster]

Redrawing the prompt and the line of text was quite deliberate. If you don't, you can't handle Backspace and instead can only support terminals that do line buffering.

[thejpster]

I think this was fixed in #9