Prefix PATH with nixd/bin/ during execution.
Add opt and var directories to hierarchy.
Remove return statement in nixd_error function.

Make nixd_error generally useful in logging to stderr.
Log with "nixd: " or "name: " in nixd_echo.
Check for sqlite3 & zmq headers for mongrel2.
Use NIXD_DIR value from environment, if set.
Implement verbose mode, needs a command-line flag.
Add var and opt to gitignore.
Add nixd ls for silent file checking.