Merge pre-4-2-20-invasive. Summary of changes:

* Acquire resources before daemonizing, fail in foreground
* Initialize threads and signals after daemonizing
* Make most file names relative to data directory
* emp_server and files make it their working directory
* emp_config() no longer screws up some file names
* Missing or incorrect econfig is now fatal
* Don't log to default log file when econfig changes it

diff --cc src/lib/empthread/ntthread.c
Simple merge

diff --cc src/lib/player/accept.c
Simple merge

diff --cc src/server/main.c
Simple merge