Negation and nested properties

• Fix visible att in popups.
• Adds nested property accessors to geojson popup text: {attributes.email}
• Adds negation to shortcode attributes with an exclamation mark: e.g. Disable all interaction with [leaflet-map address="las vegas" !boxZoom !doubleClickZoom !dragging !keyboard !scrollwheel !attribution !touchZoom]
• Fix case-sensitive boxZoom
• Add touchZoom to map attributes
• Fix icon-related anchor attributes (numbers instead of strings)