Some makefile additions.

Can be compiled with debug symbols (on by default), and debug macros
can be silenced (off by default).

Use it like
  make DEBUG_SYMBOLS=false DEBUG_LOGGING=false
Server now replies to requests.

There's a map<string, server_member_function>. If the handle matches a
fun in that map, that fun is called. I think this is a rather flexible
and elegant design.