add log4cxx-based logger (refs #746)

Add new log4cxx-based logger (#746).

This is an implementation of new logger; fix for each log output (LOG(INFO) lines etc) will be a separate pull-req. Currently still depends on glog.
If you're on Ubuntu, you'll need `liblog4cxx10-dev` package.

I noticed that `likeliness` is almost useless, because

* When compiled without `--enable-debug`, DEBUG/TRACE logs are compiled away, so this expression becomes always true.
* When compiled with `--enable-debug`, users expect DEBUG/TRACE logs, so `likeliness` makes performance worse.

I'll update the patch to include `log4cxx::LevelPtr` inside `stream_logger`. (the idea was proposed by @gintenlabo in offline discussion.)