Adds get_full_class_name_T function to all exported classes.

The idea is to provide better names for exported classes. These names will show in
new code that can traverse the "world" and report the existing userdata, tables and
so on at a given moment.
Adds module luanode.introspect

luanode.introspect should be the place to put all stuff related to
get an insight of the running VM:
- how many sockets are created right now?
- how many timers?

That information is available in luanode.introspect.counters, with functions
to retrieve each value.