Rio-tiler

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- added `reader.preview`, `reader.point` methods
- added multi_* functions to rio_tiler.reader to support multiple assets addresses
- added `rio_tiler.utils.has_mask_band` function
- added `rio_tiler.utils.get_overview_level` to calculate the overview level needed for partial reading.
- added type hints
- added scale, offsets, colormap, datatype and colorinterp in reader.metadata output (158)
- new `rio_tiler.colormap` submodule
- added `unscale` options to rio_tiler.reader._read function apply internal scale/offset (157)

Breaking Changes:
- removed python 2 support
- new package architecture (.io submodule)
- introduced new rio_tiler.reader functions (part, preview, metadata...)
- renamed rio_tiler.main to rio_tiler.io.cogeo
- bucket and prefixes are defined in rio_tiler.io.dataset.`{dataset}_parse` function from
AWS supported Public Dataset
- renamed `minimum_tile_cover` to `minimum_overlap`
- renamed `tile_edge_padding` to `padding`
- padding is set to 0 by default.
- use terracotta calculate_default_transform (see https://github.com/cogeotiff/rio-tiler/issues/56#issuecomment-442484999)
- colormaps are now have an alpha value
- `rio_tiler.utils.get_colormap` replaced by `rio_tiler.colormap.get_colormap`
- new `rio_tiler.colormap.get_colormap` supports only GDAL like colormap
- replaced `rio_tiler.utils.array_to_image` by `rio_tiler.utils.render`
- replaced `rio_tiler.utils.apply_cmap` by `rio_tiler.colormap.apply_cmap`
- replaced `rio_tiler.utils._apply_discrete_colormap` by `rio_tiler.colormap.apply_discrete_cmap`
- removed `histogram_bins` and `histogram_range` in options in metadata reader.
Should now be passed in `hist_options` (e.g: hist_options={bins=10, range=(0, 10)})
- remove alpha band value from output data array in tile/preview/metadata 127

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- Add Sentinel2-L2A support (137)
- Update Sentinel-2 sceneid schema (S2A_tile_20170323_07SNC_0 -> S2A_L1C_20170323_07SNC_0)

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- Add `warp_vrt_option` option for `utils.raster_get_stats` and `utils.tile_read` to
allow more custom VRT Warping. (ref: https://github.com/OSGeo/gdal/issues/1989#issue-518526399)
- Add `rio_tiler.utils.non_alpha_indexes` to find non-alpha band indexes (ref 127)

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- Allow `DatasetReader`, `DatasetWriter`, `WarpedVRT` input for `utils.raster_get_stats` and `utils.tile_read`
- add `minimum_tile_cover` option to filter dataset not covering a certain amount of the tile.
- add Sentinel-1 submodule

Breaking Changes:
- need rasterio>=1.1

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- reduce memory footprint of expression tiler
- fix wrong calculation for overview size in `raster_get_stats` (116)
- Add Landsat 8 QA Band (117).

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- add more colormap options (from matplotlib) and switch from txt files to numpy binaries (115)