Release v0.2.32

Apache/mod_php parity wave 2:
- Built-in overrides: php_sapi_name, filter_input/filter_input_array, header_register_callback, error_log
- $_SERVER completeness: GATEWAY_INTERFACE, REQUEST_SCHEME, HTTPS
- Directive middleware: RedirectMiddleware (mod_alias), SetEnvIfMiddleware (mod_setenvif)
- Config: ServerTokens (X-Powered-By), FileETag, default_mimetype
Fixes:
- #20 void return discarded buffered output
- #21 unset($g->session[k]) not persisted through custom handler