White-space included in field names.

[hamishmorgan]

When fields names start with, or are followed by, white-space characters, the characters are included in field token. This will cause them to produced as unknown directives. We need to adjust the parser to handle this better. A couple of options:

• White space skipping doesn't appear to be working as expected, so we could fix that.
• Alternatively, trim to token before it's produced.