Add a trim_whitespace convenience method

[JJaviMS]

Hi, I have implemented a convenience method that will help trim whitespaces when the user may need them.

There are cases when the response comes with some \r\n, which are not really necessary. Using this method, those bytes will be skipped, and the user only needs to think about the message.

Let's assume a message: \r\nAT+CPIN: READY\r\n\r\nOK\r\n, if I want to parse this when I use the library, I need to take care of putting those \r\n. Using the trim_whitespace methods, the strings will be simplified, and the headaches of checking the whitespaces will be gone.

Now the library performs the trim_space, maybe that can be replaced with the 'trim_whitespaces'.

[diondokter]

Nice!

[diondokter]

Do you have more in store? If not I'll cut a new release soon. But if you do, I'd rather wait and collect them all.

[JJaviMS]

Do you have more in store? If not I'll cut a new release soon. But if you do, I'd rather wait and collect them all.

I think this is the last one in a while :)