Rio-viz

* update to new titiler/rio-tiler/rio-cogeo version
* remove Mapbox maps and switch to `stamen` basemap
* remove python3.6 support

* use titiler custom JSONResponse to encode nan/inf/-inf values in response

* do not rescale data if there is a colormap

* add `titiler.core` as dependencies to reduce code duplication.
* update code and templates to follow `titiler.core` specs.
* add `/crop.{format}` POST endpoint to get image from polygon shaped GeoJSON (https://github.com/developmentseed/rio-viz/pull/36)
* rename `/part` to `/crop` to match TiTiler (https://github.com/developmentseed/rio-viz/pull/36)
* refactor dependencies to remove bidx in info/metadata/stats (https://github.com/developmentseed/rio-viz/pull/37)
* refactor UI (https://github.com/developmentseed/rio-viz/pull/38)
* add simple **MosaicReader** (https://github.com/developmentseed/rio-viz/pull/32)

bash
$ rio viz "tests/fixtures/mosaic_cog{1,2}.tif" --reader rio_viz.io.MosaicReader

* update rio-tiler-mvt
* use cache middleware to add `cache-control` headers.

* add dynamic dependency injection to better support multiple reader types (https://github.com/developmentseed/rio-viz/pull/28)
* add better UI for MultiBaseReader (e.g STAC)
* renamed `indexes` query parameter to `bidx`
* update bands/assets/indexes query parameter style to follow the common specification


before
/tiles/9/150/189?indexes=1,2,3

now
/tiles/9/150/189?bidx=1&bidx=2&bidx=3