fix correct shutdown after SIG{INT,TERM}

sync changelog

kill only $pid during regress testing before we did `pkill gmid', but that would influence also other instances of gmid!

quit every process cleanly when receiving SIGINT or SIGTERM

move all sandbox-related code to sandbox.c while there, add capsicum for the logger process

sync ChangeLog

refactoring: imsg everywhere use imsg to handle ALL kinds of IPC in gmid. This simplifies and shorten the code, and makes everything more uniform too.

handle SIGHUP gracefully i.e. don't print scary messages with LOG_CRIT priority!

split usage string into two lines

fix out-of-bounds access obviously msg[datalen] is an off-by-one

give each server process its own socket for the executor this fixes a bug introduced with the prefork mechanics: every server process shared the same socket, and this would cause a race condition when multiple server processes asked for a script cgi being executed. This gives each server process its own socket to talk to the executor, so the race cannot happen.

include sys/types.s to fix the build on OpenBSD

updated readme

[seccomp] allow sendmsg

sync global variables