Bulk Add Trails trail

To help auto-populate some of the trails fields, we support KML ExtendedData as SimpleData elements.

        <Placemark>
            <name>Slickrock</name>
            <ExtendedData>
                <SchemaData schemaUrl="#TrailHeadTypeId">
                    <SimpleData name="type">crosscountry</SimpleData>
                    <SimpleData name="rating">Black</SimpleData>
                    <SimpleData name="scale:imba">3</SimpleData>
                    <SimpleData name="description">text here</SimpleData>
                </SchemaData>
            </ExtendedData>
            <LineString>
                <coordinates>...</coordinates>
            </LineString>
        </Placemark>    

We also support OSM tags!

        
        <way timestamp="2014-10-25T13:03:05Z" id="-7" uid="696266" user="trailforks" visible="true" version="1">
            <tag k="name" v="Ladies Only"/>
            <tag k="description" v="rad trail..."/>
            <tag k="highway" v="path"/>
            <tag k="bicycle" v="designated"/>
            <tag k="mtb:type" v="DH"/>
            <tag k="mtb:scale:imba" v="4"/>
            ...
        </way>    

Accepted fields:

• type OR mtb:type (crosscountry, allmountain, downhill)
• rating (Green, Blue, Black, Double Black)
• mtb:scale:imba (0-4)
• description