Import from kml with HTML in description

[yohanboniface]

At this stage, when a kml file contains HTML in the description, it will be formatted by togeojson as an object : `{type: 'html', value: 'with html'.

At this point, uMap does not deal with this object at all:

• when editing the feature, the description will be [object object]
• when opening a popup, it will fail because greedyTemplate expects a string

I'm not sure how to deal with this, given we do not accept html in the description:

• put anyway the html in the description, but then all the < will be visible (it is escaped)
• keep the object, and deal with it when reading it; could work for a popup, but not when the person needs to edit it
• what to do when kml is used as remote data (it could be user friendly to be able to show the HTML as HTML)
• what do to with maps that have already been created from kml with html