Investigate trkType

[meghanhade]

Investigate why a trace in this format isn't working:

version="1.1 [1] ?"
creator="xsd:string [1] ?"> 
<metadata> metadataType </metadata> [0..1] ?
<wpt> wptType </wpt> [0..*] ?
<rte> rteType </rte> [0..*] ?
<trk> trkType </trk> [0..*] ?
<extensions> extensionsType </extensions> [0..1] ?
</gpx>```

[meghanhade]

may be related to #513