Remove use of nom from the public api

[VanillaBrooks]

Currently mentioned in the API here, which requires workarounds

vtk/src/traits.rs

Lines 303 to 311 in f698667

	pub trait Visitor<Spans>
	where
	Self: Sized,
	{
	/// The type that will be output from the visitor once parsing is complete
	type Output;
	/// The implementing type is constructed with the `read_headers` function.
	fn read_headers<'a>(spans: &Spans, buffer: &'a [u8]) -> IResult<&'a [u8], Self>;