LogC version 0.4.0

Added
* `liblogc_config` for configuration parsing using libconfig
* log function with critical level `log_fatal` and `fatal` macro that
  calls `exit()` to terminate execution of application.
* log_argp argument `--no-syslog` for daemon logs as there would be no
  way to disable default syslog otherwise.

Changed
* Syslog configuration is now no longer configured using boolean in the
  log structure but rather by using functions with default handled the
  same way as for standard error fallback output.

Removed
* log_argp argument `--no-stderr` as it is easy to redirect or drop
  standard error output without needing this option