Consider not to tolerate line breaks in bencoded data

[josecelano]

Relates to: #14 (comment)

@da2ce7 asked why we tolerate line breaks in bencoded data.

I think I only added it to tolerate the line break at the end of the bencode value because it makes it more flexible to run the application like this:

echo "4:spam" | cargo run

If we don't tolerate line breaks, you only can use this:

printf "4:spam" | cargo run

I don't like it. Maybe we should "clean" the input stream only in the main app (when we are reading from stdinput).

cc @da2ce7