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

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