Changes
### Added
- Add .gdbinit files from released PHP versions #996
- Support PHP 5.5 #1008, #1018, #1020, #1030, #1032
- Add PHP 5.4 support to PECL package #1019
- Add Levi and Luca as lead developers to package.xml #1025
- Close open spans on fatal errors #1028
- Attach fatal errors to all open internal spans #1034
- Experimental PHP 8.0.0 RC 1 support (Provided for testing only and not intended for use on production) #1027 #1036 #1041
### Changed
- Enable the background sender by default on PHP 5.4 #991
- Remove userland references to sandboxing #1003
- Sandbox flush in limited mode on PHP 5.4 #1009
- Defer loading of PDO, Memcached, Slim, WordPress, and Yii integrations until first usage #1006
- Clear separation in testing of src/api vs src/DDTrace #1017
- Harden curl integration #1024
- Compile src/DDTrace/version.php into _generated.php to avoid loading it at runtime #1026
- Disable instrumenting generators on PHP 5 #1050
### Fixed
- Fix pecl-build for real releases #998
- Properly group traces sent in batch during long running scripts #1029
- Add back support for trace analytics to curl integration #1031