Add support for pmtiles output format (#55)

* add pmtiles.hpp from github.com/protomaps/PMTiles [#10]

* tippecanoe main writes pmtiles output. [#10]

* detect output format using suffix
* after mbtiles is done writing, replace with pmtiles based on map/image tables.
* add method to write_json for writing json sub-object.

* tippecanoe-decode reads pmtiles input. [#10]

* tile-join reads and writes pmtiles. [#10]

* pmtiles test suite for decode and tile-join [#10]

* add base GitHub CI action for compiling and test suite.

* update pmtiles.hpp with z>15 fix

* Fix some ordering problems with pmtiles decode

* Pmtiles should also pass the raw tiles tests

* Eradicate spaces from tileset metadata JSON fields

* Eradicate spaces from more test fixtures

* Update more tests

* Pmtiles tests pass now too

* Remove unnecessary sort (and make indent)

* Update changelog

* The allow-existing test for pmtiles needs -o, not -e

* Declare --allow-existing to be unsupported for pmtiles.

It was always a bad idea even for mbtiles.

Co-authored-by: Brandon Liu <bdon@bdon.org>

pmtiles_file.hpp

@@ -0,0 +1,16 @@
+#ifndef PMTILES_FILE_HPP
+#define PMTILES_FILE_HPP
+
+#include "pmtiles/pmtiles.hpp"
+#include "mbtiles.hpp"
+
+bool pmtiles_has_suffix(const char *filename);
+void check_pmtiles(const char *filename, char **argv, bool forcetable);
+
+void mbtiles_map_image_to_pmtiles(char *dbname, metadata m, bool tile_compression, bool quiet, bool quiet_progress);
+
+std::vector<pmtiles::entry_zxy> pmtiles_entries_tms(const char *pmtiles_map, int minzoom, int maxzoom);
+std::pair<uint64_t, uint32_t> pmtiles_get_tile(const char *pmtiles_map, int z, int x, int y);
+sqlite3 *pmtilesmeta2tmp(const char *fname, const char *pmtiles_map);
+
+#endif