Massive refactoring of all code + audio skeleton.

This should make it easier to find files and (in the future) split things
up into separate libraries.
It also changes around emulator initialization to make it a little more
difficult to do things out of order and a little more sensible as to when
real init work happens.
Also adding a skeleton audio system/driver and reworking CPU register
access to be more extensible.

src/xenia/cpu/global_exports.cc

@@ -15,13 +15,12 @@
 #include <xenia/cpu/sdb.h>
 #include <xenia/cpu/ppc/instr.h>
 #include <xenia/cpu/ppc/state.h>
-#include <xenia/kernel/export.h>
+#include <xenia/export_resolver.h>
 
 
 using namespace xe;
 using namespace xe::cpu;
 using namespace xe::cpu::sdb;
-using namespace xe::kernel;
 
 
 namespace {