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/tests/test_mod.py

@@ -0,0 +1,31 @@
+"""Module tests"""
+
+from mercantile import Tile
+import pytest
+
+import rio_pmtiles.worker
+
+
+@pytest.mark.parametrize("tile", [Tile(36, 73, 7), Tile(0, 0, 0), Tile(1, 1, 1)])
+@pytest.mark.parametrize("filename", ["RGB.byte.tif", "RGBA.byte.tif"])
+def test_process_tile(data, filename, tile):
+    sourcepath = str(data.join(filename))
+    rio_pmtiles.worker.init_worker(
+        sourcepath,
+        {
+            "driver": "PNG",
+            "dtype": "uint8",
+            "nodata": 0,
+            "height": 256,
+            "width": 256,
+            "count": 3,
+            "crs": "EPSG:3857",
+        },
+        "nearest",
+        {},
+        {},
+    )
+    t, contents = rio_pmtiles.worker.process_tile(tile)
+    assert t.x == tile.x
+    assert t.y == tile.y
+    assert t.z == tile.z