- Close open sandboxed spans on exit (PHP 5) #780
- Prehook feature to run tracing closures before the original call #784
### Changed
- Enable background sender (BGS) by default #796, #800
- Improves alpine extensions build/verify process #774
- Refactor Symfony integration #786
- Let curl calculate Content-Length header value when sending requests to the agent #804
### Fixed
- Pass return value as null to tracing closure when value IS_UNDEF #791 (thanks for the report @wajdisawaf!)
- Set a sane memory limit when running php from inside post-install hook #792