New encoding options: encUseCrLf and encIncludeHeader

[pjones]

• encUseCrLf: Controls the record separator when encoding. The
  default is True which preserves the current behavior of using \r\n.
  Using False changes the behavior to use \n.
• encIncludeHeader: Allow control over whether a header row is
  included when encoding records. The default is True to maintain
  current behavior. This allows records to be encoded in a streaming
  fashion. The first batch of encoded records can include a header,
  and remaining batches can omit it.

[pjones]

I just wanted to note that I added strictness annotations to the new members of the EncodeOptions type because the existing field already had one. I also thought about adding an INLINE pragma for the new recordSep function but though it would be a bit premature and it would be best to leave that up to you.

Thanks!