PLYLoader: Fix for linesplitting on universal newlines

[gwegash]

Description

• PLYLoader would split lines successfully if they were \r\n or \n but not \r.
• Some .ply files can be encoded with \r
• The spec is quite ambiguous here. So supporting universal newlines looks like the best thing to do.

This PR fixes the problem by allowing line splitting on \r characters too, so the PLYLoader should now support universal newlines.

[Mugen87]

Normally, carriage returns should only be used in the header however not every exporter follows this convention since the spec is not specific enough. That's indeed unfortunate.

It's probably best to accept any line ending style in the loader.

[mrdoob]

Thanks!