Bug: Not closed tags

[shikhalev]

"Save as" make invalid file with some unclosed tags.

    <extensions>
      <line xmlns="http://www.topografix.com/GPX/gpx_style/0/2">
        <color>0000FF</color>
        <opacity>0.59</opacity>
        <width>6.0</width>
        <extensions>
          <locus:lscolorbase>#960000FF</locus:lscolorbase>
          <locus:lswidth>6.0</locus:lswidth>
          <locus:lsunits>PIXELS</locus:lsunits>
    </extensions>

see lines 15-24 in 2021-07-25_14-06-38_edited.gpx

files.zip