Skip the header and bad data in CSV parsing

[tschaub]

In the CSV parsing examples, the prevIndex === 0 condition is never met, so the first coords created have NaN values. The filter-points-webgl example still works because the renderer gets all features in the "infinite" extent. When this same parsing logic is used with a regular vector layer, no features are rendered because of the one(s) with NaN coordinates (one for the header line and one later in the file with no lon/lat).

[ahocevar]

Nice, thanks!