Add --generate-variable-depth-tile-pyramid option (#251)

* Track output position at the file level instead of within each tile

* Track file position where the child tile data begins

* Add option and document its intended behavior

* Changing the detail loop to account for stopping early

* I forgot I already added an option for this

* Stop early if we can make a complete tile

* Add a test of zoom truncation with limited feature count

* Forgot to commit the actual code change

* Make room for a vertex count in the header of each serialized tile

* Estimate tile complexity; don't try truncating when unlikely to work

* Be more conservative, because ever retrying a tile is a big speed hit

* If stopping early, don't simplify or clean; leave that to overzoom

* Add tiny polygon reduction / dust to overzoom

* Don't try to stop early in the children if we dropped anything by rate

* Fflush here too before pwriting

* Don't stop early if we ended up dropping any features.

Rework the can-the-next-zoom-stop-early logic to avoid going
one zoom further than needed.

* Fix warning

* Fix warnings

* Oops, checking for the wrong expected return value

* Cleanup from adding line simplification in overzoom

* Current (wrong) behavior when combining coalescing and truncating

* Keep a list of parent tiles to skip rather than truncating

* Now the coalesced tiles in z12 get children in z13

* Don't double-count feature dropping when the zoom level is retried

* Correct README description

* Remove todo about special case below basezoom, which is accounted for

* Be a little more aggressive in drop-densest determination

* Scale tile feature limit for megatiles in the same way as byte limit

* Fully deprecate -detect-shared-borders into an alias

* Track the distances found in the douglas-peucker recursion

* Serialize and deserialize the distance with the vertices

* Revert "Serialize and deserialize the distance with the vertices"

This reverts commit 753f1b7909.

* Revert "Track the distances found in the douglas-peucker recursion"

This reverts commit e5361f8c22.

* Revert "Fully deprecate -detect-shared-borders into an alias"

This reverts commit 0698aeb766.

* Better tracking of whether we failed to make a full-detail tile

* Put a bloom filter in front of the binary search for shared nodes

* Forgot to take out this printf

* Improve dispatch of tiling tasks

* Still dispatch the biggest tasks first

* Track zoom truncation in the strategies list in the tileset metadata

* Prescan for small deltas before doing proper simplification

* Revert "Prescan for small deltas before doing proper simplification"

This reverts commit d1d8238b83.

* Update version and changelog

* Rename to --generate-variable-depth-tile-pyramid

serial.cpp

@@ -131,12 +131,12 @@ void deserialize_ulong_long(const char **f, unsigned long long *zigzag) {
 
 	while (1) {
 		if ((**f & 0x80) == 0) {
-			*zigzag |= ((const unsigned long long) **f) << shift;
+			*zigzag |= ((unsigned long long) **f) << shift;
 			*f += 1;
 			shift += 7;
 			break;
 		} else {
-			*zigzag |= ((const unsigned long long) (**f & 0x7F)) << shift;
+			*zigzag |= ((unsigned long long) (**f & 0x7F)) << shift;
 			*f += 1;
 			shift += 7;
 		}
@@ -407,7 +407,7 @@ static void add_scaled_node(struct reader *r, serialization_state *sst, draw g)
 	long long y = SHIFT_LEFT(g.y);
 
 	struct node n;
-	n.index = encode_quadkey((unsigned) x, (unsigned) y);
+	n.index = encode_vertex((unsigned) x, (unsigned) y);
 
 	fwrite_check((char *) &n, sizeof(struct node), 1, r->nodefile, &r->nodepos, sst->fname);
 }