rio-pmtiles python package [#338] (#542)

Add rio-pmtiles command line tool. [#338]

This is derived from the original mapbox/rio-mbtiles implementation, with changes:

* output PMTiles only instead of MBTiles.
* Python 3.7+ only.
* remove --implementation, --image-dump, --append/--overwrite, --covers features.
* bump dependency versions.
* better progress reporting; add pyroaring. 
* update README and license texts.
* rio-pmtiles v0.0.6 on PyPI

python/rio-pmtiles/README.rst

@@ -0,0 +1,113 @@
+rio-pmtiles
+===========
+
+A plugin for the
+`Rasterio CLI <https://github.com/rasterio/rasterio/blob/main/docs/cli.rst>`__
+that exports a raster dataset to the PMTiles (version 3) format. Features
+include automatic reprojection and concurrent tile generation.
+
+This is derived from the original rio-mbtiles CLI by Sean Gillies at Mapbox. See CHANGELOG.md for differences.
+
+Usage
+-----
+
+.. code-block:: console
+
+    Usage: rio pmtiles [OPTIONS] INPUT [OUTPUT]
+
+      Export a dataset to PMTiles (version 3).
+
+      The input dataset may have any coordinate reference system. It must have
+      at least three bands, which will be become the red, blue, and green bands
+      of the output image tiles.
+
+      An optional fourth alpha band may be copied to the output tiles by using
+      the --rgba option in combination with the PNG or WEBP formats. This option
+      requires that the input dataset has at least 4 bands.
+
+      The default quality for JPEG and WEBP output (possible range: 10-100) is
+      75. This value can be changed with the use of the QUALITY creation option,
+      e.g. `--co QUALITY=90`.  The default zlib compression level for PNG output
+      (possible range: 1-9) is 6. This value can be changed like `--co
+      ZLEVEL=8`.  Lossless WEBP can be chosen with `--co LOSSLESS=TRUE`.
+
+      If no zoom levels are specified, the defaults are the zoom levels nearest
+      to the one at which one tile may contain the entire source dataset.
+
+      If a title or description for the output file are not provided, they will
+      be taken from the input dataset's filename.
+
+      This command is suited for small to medium (~1 GB) sized sources.
+
+      Python package: rio-pmtiles (https://github.com/protomaps/PMTiles).
+
+    Options:
+      -o, --output PATH               Path to output file (optional alternative to
+                                      a positional arg).
+
+      --title TEXT                    PMTiles dataset title.
+      --description TEXT              PMTiles dataset description.
+      --overlay                       Export as an overlay (the default).
+      --baselayer                     Export as a base layer.
+      -f, --format [JPEG|PNG|WEBP]    Tile image format.
+      --tile-size INTEGER             Width and height of individual square tiles
+                                      to create.  [default: 256]
+
+      --zoom-levels MIN..MAX          A min...max range of export zoom levels. The
+                                      default zoom level is the one at which the
+                                      dataset is contained within a single tile.
+
+      -j INTEGER                      Number of workers (default: number of
+                                      computer's processors).
+
+      --src-nodata FLOAT              Manually override source nodata
+      --dst-nodata FLOAT              Manually override destination nodata
+      --resampling [nearest|bilinear|cubic|cubic_spline|lanczos|average|mode|gauss|max|min|med|q1|q3|rms]
+                                      Resampling method to use.  [default:
+                                      nearest]
+
+      --version                       Show the version and exit.
+      --rgba                          Select RGBA output. For PNG or WEBP only.
+
+      -#, --progress-bar              Display progress bar.
+      --cutline PATH                  Path to a GeoJSON FeatureCollection to be
+                                      used as a cutline. Only source pixels within
+                                      the cutline features will be exported.
+
+      --oo NAME=VALUE                 Format driver-specific options to be used
+                                      when accessing the input dataset. See the
+                                      GDAL format driver documentation for more
+                                      information.
+
+      --co, --profile NAME=VALUE      Driver specific creation options. See the
+                                      documentation for the selected output driver
+                                      for more information.
+
+      --wo NAME=VALUE                 See the GDAL warp options documentation for
+                                      more information.
+
+      --exclude-empty-tiles / --include-empty-tiles
+                                      Whether to exclude or include empty tiles
+                                      from the output.
+
+      --help                          Show this message and exit.
+
+Performance
+-----------
+
+The rio-pmtiles command is suited for small to medium (~1 GB) raster sources.
+On a MacBook Pro M1, the 1:10M scale Natural Earth raster
+(a 21,600 x 10,800 pixel, 700 MB TIFF) exports to PMTiles (levels 1 through 5)
+in 15 seconds.
+
+.. code-block:: console
+
+    $ time GDAL_CACHEMAX=256 rio pmtiles NE1_HR_LC.tif \
+    > -o ne.pmtiles --zoom-levels 1..5 -j 4
+
+    14.87s user 10.40s system 258% cpu 9.787 total
+
+Installation
+------------
+
+``pip install rio-pmtiles``