Unsanitized headers can break body in response
I was creating some custom headers to add to my response, and was using IDE magic to replicate some lines, which resulted in my last header arguement still containing trailing \c\L chars.

My initial presumption was this would be appropriately handled by the library, but it was not, and caused my resulting response body to be missing characters as the \c\L essentially caused overflow into where the body was expected to start.

An easy solution on my end was 

```nim
 let sanitizedHeaders = HEADERS.strip(leading = false, chars = {'\c', '\L'})
```

before inserting the headers in `send`

I am wondering if you're of the opinion that the library should in fact handle this, or if it's up to the user to sanitize. I understand this is supposed to be performance-oriented and such finer details may be left out for performance reasons, however, it also exposes an `unsafeSend` and `send` method, and when such a distinction occurs, I would presume it's pretty hard to shoot myself in the foot with `send`, yet I accomplished it just via adding some basic headers.

Another option which would lessen the impact on `send` (instead of doing a check/strip on each call) would be a method exposed to the user to create a HttpBeast safe and compatible header string.