Add logging functions with selectable log output targets Currently, our "logging" consists of a mix of printf(), perror(), and other such calls which print output to stdout/stderr. In normal usage, browser-switchboard will be launched by D-Bus, which results in stdout/stderr pointing to /dev/null and debugging output being lost. To improve this situation, introduce a new set of logging functions log_out() and log_perror(), and a log_config() which allows choosing the log target. These functions log to stdout by default, but also support syslog output (to the LOG_USER facility, with priority LOG_DEBUG) and disabling logging entirely. Thanks to Faheem Pervez (qwerty12) for the suggestion.