update CHANGELOG in anticipation of v3.0.12 release

CHANGELOG.md

@@ -6,6 +6,37 @@ Developers: Please commit along with changes.
 
 For a complete change history, see the git log.
 
+## 3.0.12
+
+Released:?????
+
+(Packaged from xxxxxx)
+
+#### Summary
+
+- Ensured gdal.input is registered once (refs #3093 #3339 #3340)
+- Fixed `mapnik::util::is_clockwise` implementation to use coordinates relative to the origin and avoid numeric precision issues
+- `mapnik-index` is updated to fail on first error in input (csv)
+- Added `guard` to `get_object_severity` method (ref #3322)
+- Improved `hash` calculation for `mapnik::value` (ref #3406)
+- AGG - made cover `unsigned` to avoid left shift of negative values (ref #3406)
+- Fixed using `scale_factor` in `evaluate_transform(..)`
+- Fixed line spacing logic by applying `scale factor`
+- ~~Fixed `stringify_object/stringify_array` implementations by disabling white space skipping (ref #3419)~~
+- Added geojson unit test for property types/values
+- JSON - added support for object and array type in `json_value` and update `stringifier`
+- GDAL.input - fallback to using `overviews` if present (8e8482803bb435726534c3b686a56037b7d3e8ad)
+- TopoJSON.input - improved and simplified grammer/parser implementation (https://github.com/mapnik/mapnik/pull/3429)
+- GDAL.input - Added support for non-alpha mask band
+- TopoJSON.input - fixed order of ellements limitation (ref #3434)
+- Fixed stroke-width size not included in markers ellipse bounding box (ref #3445)
+- Implemented `char_array_buffer` and removed `boost::iostreams` dependency (2e8c0d36c2237f2815d8004c1b96bad909056eb9)
+- JSON.input - `extract_bounding_box_grammar` - make features optional (ref #3463)
+- Ensure input plugins return `empty_featureset` rather than `nullptr` (feature_ptr())
+- Added support for quantising small (less than 3 pixel) images (ref #3466)
+- Added support for natural logarithm function in expressions (ref #3475)
+
+
 ## 3.0.11
 
 Released: