a simple logging system

to make development and bug search easier, I've added a proper logging system. It allows for three different severity levels (info, warning, error) and two verbosity levels. (on chatty, each log msg also displays file name and line number)

Usage is quite simple

```
INFO("a test message")
```

gives us

```
2013-05-06 01:18.03 -       0ms [INFO]  a test message (hello.cpp:12)
```

(those are milliseconds since program start)