Map enhancements

[thomasneirynck]

WIP, hold off on review. Opening PR for visibility, but not intended to be merged.

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[UPDATE SINCE 02/07/2017]

This PR needs to introduce two large changes to the mapping support

• the addition of Vector maps: Vector Maps / Choropleth Maps / Shapefile based fill maps #5039
• bug fixes and enhancements to the existing tilemap
  • will also include some light refactoring to accommodate reuse of the mapping component for both vector maps and tilemaps.
  • includes selection of the scope outlined in Tilemap completeness #8944.
    • smoother controls: (touch support, scroll zooming, no flickering between zooming [Map] Enable Zoom with scroll wheel #7778, Mouse wheel / touchpad pinch support for map zoom #2645, Map is recreated too often #8823)
    • better heatmap defaults (High settings of max zoom make heat map not accurately reflect the data #8763)
    • polygon drawing (Geo polygon support in maps #7572)
    • Geocentroid support (Geo centroid metric aggregation type added #9676/ Use geo-centroid aggregator for geo-hash grids #5464): should not use Metric UI, but centroid positioning should be the new default behavior. (merge in original commits to preserve community contributions)

Needs further discussion:
- improve filtering behavior of bounding box control (#3731): needs to be evaluated how this is going to work on dashboards with multiple maps / saved dashboards
- limiting results based on current map extent should be merged in as well (#8087): there's broad agreement that we want it in, but not quite sure if want it as a global filter/filter tied to the visualization.

[thomasneirynck]

After review, we will split this up into 2 different PRs:

• addition of Vector Maps and associated map refactor so we can share the map implementation: This will also include the improvements to the scroll/touch zoom and the flicker issue
• new features:
  • geocentroid support, polygon drawing
  • possible changes to filtering and requesting data on demand (needs to be discussed further what we want there)