- Use multiple radius sockets to allow more concurrent authentication requests

- Use multiple radius sockets to allow more concurrent authentication requests
- Add gcc __attribute__ to logging functions
- Fix warnings shown by __attribute__
- Make sure regular cleanup happens regularly under high load
- Add variable cleanup_interval for changing cleanup interval
- Add support for reading more than one packet per fd in each processing loop
- This is configurable with the multi_read_count variable
- Remove segv handler so core dumps can happen
- Use nonblocking sockets
- Increase tun queue length
- Fix minimum length of IP packets
- Remove per-packet plugin hooks (they are slow)
- Don't drop session if no free RADIUS
- Don't expire more than 1000 sessions per cleanup interval
- Remove -a and -c command-line options. They don't work anyway
- Don't require file: in log_filename