Django-gisserver

* Improve XPath matching support, allow "app:" prefix and root elements.
* Refactored `FeatureType.resolve_element()` to return an `XPathMatch` object

* Added unpaginated GeoJSON support (performance is good enough).
* Added basic support for non-namespaced `FILTER` queries, and `PropertyName` tags (though being WFS2 attributes, clients still use them).
* Added extra strict check that `ValueReference`/`Literal`/`ResourceId` nodes don't have child nodes.
* Fixed allowing filtering on unknown or undefined fields (XPaths are now resolved to known elements).
* Optimized results streaming by automatically using a queryset-iterator if possible.
* Optimized GeoJSON output by no longer selecting the other geometry fields.
* Added shortcut properties to `XsdComplexType`: `gml_elements` and `complex_elements`.

* Added preliminary support to render complex field types (e.g. relations).
* Added `FeatureType.check_permissions()` hook to allow permission checking by subclasses.
* Added `WFSMethod.validate()` hook that allows request validation.
* Added CSV output format support.
* Added infinite pagination support.
* Added pagination size settings: `GISSERVER_DEFAULT_MAX_PAGE_SIZE`, `GISSERVER_CSV_MAX_PAGE_SIZE`.
* Added internal `XsdComplexType` class to support complex data schema definitions.
* Replaced many `FeatureType` methods to create a stable fields definition API.
* Replaced `FeatureType.fields_with_type` with `FeatureType.xsd_type` that returns an `XsdComplexType`.
* Optimized `GetFeature` responses by omitting a `COUNT` query for the last page.
* Optimized `GetFeature` responses by omitting the binary geometry data for DB-optimized rendering.
* Changed default page size / `DefaultMaxFeatures` to 5000.
* Fixed detecting `AutoField` as integer for Django 2.2.
* Fixed fallback datatype for unknown model fields (should be `xsd:anyType`, not `xsd:any` which is an element).
* Fixed fallback datatype for unknown geometry fields (should be `gml:GeometryPropertyType`, not gml:AbstractGeometryType).
* Fixed error messages for currently unsupported multiple-query KVP requests (e.g. `TYPENAMES=(A)(B)`).
* Fixed raising `InvalidParameterValue` for runtime errors in a custom `WFSView.get_feature_types()` implementation.
* Enforce using keyword-arguments on `FeatureType(...)`
* Internal code reorganizations/cleanups.

* Added database-based rendering for GML/GeoJSON (disable with `GISSERVER_USE_DB_RENDERING=False`).
* Added `has_custom_backend` to CRS class.
* Improved rendering performance for python-based GML output.
* Improved `DescribeFeatureType` to show which geometry type is used in a geometry field.
* Fixed XML output error for pagination.
* Internal code reorganizations/cleanups.

* Added `RESOURCEID` parameter support.
* Added `GetFeatureById` support.
* Added basic support for defining stored procedures.
* Added GML rendering for Polygon / MultiGeometry / MultiLineString / MultiPoint / LineString / LinearRing data.
* Fix `<fes:ResourceId>` parsing and type selection.
* Fix output errors because of `AttributeError` in `ForeignKey` fields.
* Fix `DateTimeField` being represented by an `xs:date` instead of `xs:dateTime`.
* Internal code reorganizations/cleanups.

* Added `GetPropertyValue` support.
* Added empty `ListStoredQueries`/`DescribeStoredQueries` operations nearing Simple WFS conformance.
* Added a lot of built-in FES functions.
* Added `FeatureType(fields=...)` to limit which fields are exposed (can also use `__all__`).
* **Backwards incompatible:** by default no fields are exposed, unless they are mentioned.
* Added pagination links to GeoJSON response, based on WFS 3.0 DRAFT.
* Changed `max_page_size` to reasonable 1000 per page.
* Fixed `SRSNAME` support on GeoJSON output to select the coordinate reference system.
* Fixed `ResourceId` to extract the ID from the typename.id value.
* Improved performance of output streaming (buffering output, reducing yield).
* Removed lxml dependency, as it's only used for tests.
* Internal code reorganizations/cleanups.