Multi-geometry feature indices

[kylebarron]

Related to picking... presumably the default picking gives the index of the data array? If you do this, then you have to do like a binary search into the indices array to find the feature index that contains the specified geometry (or maybe vertex?) index.

Alternatively, similarly to the geojson layer, you could pass in a feature index per vertex that maps to the geometry index. See
https://github.com/visgl/deck.gl/blob/6e6b48b82aa498b957ac775db15e62523c0c6e45/modules/layers/src/geojson-layer/geojson-layer-props.ts#L120

[kylebarron]

Fixed from #49

[kylebarron]

Though auto-highlight doesn't work for multi polygons yet