Gromox 0.18

Changes:

• http: Split some unspecific HTTP 500 errors into 500, 502, 503, 504.
• http: Incomplete RTF documents are now decoded rather than "Not Found" being emitted.
• mod_cache: added the /web path to the built-in defaults
• mod_fastcgi: fix php-fpm yielding Not Found for /web
• mod_fastcgi: changed the underlying path of the built-in rule for /web to /usr/share/grammm-web

Fixes:

• zcore: moving mails between two stores had erroneously used the old mail folder's id for deletion and failed.
• daemons: Fix a crash when programs shut down before entering the mainloop.