* DECKGL integration
Adding a new set of geospatial visualizations building on top of the
awesome deck.gl library. https://github.com/uber/deck.gl
While the end goal it to expose all types of layers and let users bind
their data to control most props exposed by the deck.gl API, this
PR focusses on a first set of visualizations and props:
* ScatterLayer
* HexagonLayer
* GridLayer
* ScreenGridLayer
* Addressing comments
* lint
* Linting
* Addressing chri's comments
* ColorSchemeControl: fixing bad use of PropTypes
Accessing PropTypes via the main React package is deprecated, and will be
removed in React v16.0. Use the latest available v15.* prop-types package from
npm instead. For info on usage, compatibility, migration and more, see
https://fb.me/prop-types-docs
* Control: adding PropTypes.func in types allowed inside `value` prop
This removes a warning during yarn tests
Fix#3589
* tests(QueryStateLabel): removing missing prop warning
```
Warning: Failed prop type: The prop `query` is marked as required in
`QueryStateLabel`, but its value is `undefined`.
in QueryStateLabel
```
* SaveQuery: removing invalid prop `target` supplied to `Overlay`.
This removes a warning during yarn tests:
```
Warning: Failed prop type: Invalid prop `target` supplied to `Overlay`.
```
* RunQueryActionButton: removing `isRequired` from queryState props
This removes a warning during yarn tests:
```
Warning: Failed prop type: The prop `queryState` is marked as required in
`RunQueryActionButton`, but its value is `null`.
```
* Adding annotations to backend
* Auto fetching Annotations on the backend
* Closing the loop
* Adding missing files
* annotation layers UI
for https://github.com/apache/incubator-superset/issues/3502
* a few fixes per code review.
- add annotation input sanity check before add and before update.
- make SelectAsyncControl component statelesis, and generic
- add annotation description in d3 tool tip
- use less variable to replace hard-coded color
* Allow for multiple color schemes
1. create ColorSchemeControl component
2. using the same new control component for linear colors
* add color spectum for linear color scheme
* remove dup css
* fix controls setting for linear color scheme
* minor fix by code review comment
* [explore] DatasourceControl to pick datasource in modal
Makes it easier to change datasource, also makes it such that the list
of all datasources doesn't need to be loaded upfront.
* Adding more metadata
