Logging service for RCE modules

Classes Logger and PtyLogger in namespace quarks::service are now available from quarks/trunk as of revision 1086 of the repository. PtyLogger is still a little delicate because it assumes that your telnet session is using /dev/pty0. This is normally true unless you start a new session while keeping /dev/pty0 open in your own code. The implementation may also not be thread-safe although the class code itself is reentrant.

Example logging to the telnet socket:

#include "quarks/service/Logger.hh"
#include "quarks/service/PtyLogger.hh"
using quarks::service::Logger;
using quarks::service::PtyLogger;

extern "C" void rce_appmain() {
  // Log to telnetd PTY, filter out severity less than Info.
  Logging::initLogging(Logger::Info, new PtyLogger());
  Logger().info("Hello");
  Logger().debug("Extra stuff"); // Filtered out.
}