Rearranged the packet and serial code to make more sense

This mostly just reimplements the best parts of the discarded branch:

> discard-encapsulated-packets

There may still be some work needed.

client/scenes/in_world.hpp

@@ -27,6 +27,7 @@
 
 //networking
 #include "udp_network_utility.hpp"
+#include "serial_packet.hpp"
 
 //graphics
 #include "image.hpp"

client/scenes/lobby_menu.hpp

@@ -31,6 +31,7 @@
 //utilities
 #include "config_utility.hpp"
 #include "udp_network_utility.hpp"
+#include "serial_packet.hpp"
 
 //client
 #include "base_scene.hpp"

client/scenes/makefile

@@ -1,5 +1,5 @@
 #config
-INCLUDES+=. .. ../../common/gameplay ../../common/graphics ../../common/map ../../common/network ../../common/network/packet ../../common/network/serial ../../common/ui ../../common/utilities
+INCLUDES+=. .. ../../common/gameplay ../../common/graphics ../../common/map ../../common/network ../../common/network/packet_types ../../common/ui ../../common/utilities
 LIBS+=
 CXXFLAGS+=-std=c++11 $(addprefix -I,$(INCLUDES))