**Deprecation notice**:
- Setting service name via `DD_SERVICE_NAME` is now deprecated and will be removed in a future release. Use `DD_SERVICE` instead for consistency with other Datadog tracers and services.
- Setting global tags via `DD_TRACE_GLOBAL_TAGS` is now deprecated and will be removed in a future release. Use `DD_TAGS` instead (with the same format) for consistency with other Datadog tracers and services.
- `DD_TRACE_RESOURCE_URI_MAPPING` is deprecated now that it has been split into `DD_TRACE_RESOURCE_URI_MAPPING_INCOMING` and `DD_TRACE_RESOURCE_URI_MAPPING_OUTGOING`.
- The functions `dd_trace` and `dd_trace_forward_call` are deprecated and will be made a no-op in the next release. See #924 for how to migrate.

### Added

- Apply new uri to resource normalization rules #928
- Add DDTrace namespace for internal functions #930
- Startup logging (can be disabled by setting `DD_TRACE_STARTUP_LOGS=0`) #935

### Changed

- Sandboxed cURL (PHP 5) #911, #938
- Sandbox Lumen (PHP 5) #945
- Sandboxed Symfony (PHP 5) #946
- Add support for service name configuration via DD_SERVICE #919
- Add support for DD_TAGS, fallback to DD_TRACE_GLOBAL_TAGS #920
- Add support for DD_VERSION and DD_ENV variables #803 - thanks @brettlangdon
- Enable OpenTracing test suite in CI #921
- Defaults for name and resource on SpanData #923
- Refactor dispatch.{c,h} #932
- Extract ddtrace_sandbox_begin/ddtrace_sandbox_end helpers #940
- Warn on dd_trace usage if DD_TRACE_WARN_LEGACY_DD_TRACE #941

### Fixed

- Only build on 64-bit platforms #929 (thanks for the report @remicollet)
- (PHP 5.4) Make compilation to single file compatible with `include __DIR__ . '...'` in files #943