Extra coordinate precision; feature ordering; compression improvements

* Add an option to retain extra coordinate precision at maxzoom

* Make sure not to shift away the extra detail from coordinates

* Add an option to convert double-precision attributes to single

* Sort attribute values in tiles to make them compress a little better

* Slightly improve polygon simplification

By choosing a point that would be retained after simplification
to be the start/end point that always gets retained

* I regret making all of these tests involve polygons

* Add an option to specify the size of tiny polygons

* Fix accidental requiring of argument for --single-precision

* Guard against duplicate points when generating "sizes" for them

* Restore the intended behavior that tiny polygons don't get simplified

* Make the extra detail settable rather than always maximizing it

* Revert "Improve maxzoom guessing for tightly-clustered point data sources (#4)"

This reverts commit fec5e8354c.

* Add an option to prevent choosing a base zoom higher than the maxzoom

* Keep the drop rate high enough when the basezoom gets constrained

* Revert "Revert "Improve maxzoom guessing for tightly-clustered point data sources (#4)""

This reverts commit db6bc27d9e.

* Add --order-by and --order-descending options

* Accept multiple --order-by and --order-descending-by sort keys

options.hpp

@@ -29,6 +29,7 @@
 #define P_SIMPLIFY ((int) 's')
 #define P_SIMPLIFY_LOW ((int) 'S')
 #define P_SIMPLIFY_SHARED_NODES ((int) 'n')
+#define P_SINGLE_PRECISION ((int) 'N')
 #define P_FEATURE_LIMIT ((int) 'f')
 #define P_KILOBYTE_LIMIT ((int) 'k')
 #define P_DYNAMIC_DROP ((int) 'd')
@@ -42,6 +43,7 @@
 #define P_USE_SOURCE_POLYGON_WINDING ((int) 'w')
 #define P_REVERSE_SOURCE_POLYGON_WINDING ((int) 'W')
 #define P_EMPTY_CSV_COLUMNS ((int) 'e')
+#define P_BASEZOOM_ABOVE_MAXZOOM ((int) 'b')
 
 extern int prevent[256];
 extern int additional[256];