geojson lines writer

[kylebarron]

This works for features but not geometries because it's hard to know when to insert the \n to end the line.

[michaelkirk]

Whoops, sorry that this sat here so long. I forgot about it.

Feel free to merge after addressing that last small change.

[kylebarron]

It turns out that passing idx instead of 0 fails the test for the feature, but it also doesn't pass the geometry test. For example, when logging to stdout I see:

failures:

---- geojson::geojson_line_writer::tests::good_geometries stdout ----
a: {"type": "Point", "coordinates": [1.1,1.2]}
b: { "type": "Point", "coordinates": [1.1, 1.2] }
a: ,{"type": "Point", "coordinates": [2.1,2.2]}
b: { "type": "Point", "coordinates": [2.1, 2.2] }
thread 'geojson::geojson_line_writer::tests::good_geometries' panicked at geozero/src/geojson/geojson_line_writer.rs:227:73:
called `Result::unwrap()` on an `Err` value: Error("expected value", line: 1, column: 1)

Because the idx passed into begin_point is >0, a comma gets added here

geozero/geozero/src/geojson/geojson_writer.rs

Lines 22 to 27 in 458f38c

	fn comma(&mut self, idx: usize) -> Result<()> {
	if idx > 0 {
	self.out.write_all(b",")?;
	}
	Ok(())
	}

[kylebarron]

I found a workaround and added a comment. Let me know if that solution is ok. Also, I don't have merge access.