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/gpu/ring_buffer_worker.cc

@@ -570,7 +570,7 @@ uint32_t RingBufferWorker::ExecutePacket(PacketArgs& args) {
           switch (type) {
           case 0x4: // REGISTER
             index += 0x2000;
-            for (int n = 0; n < count - 1; n++, index++) {
+            for (uint32_t n = 0; n < count - 1; n++, index++) {
               uint32_t data = READ_PTR();
               const char* reg_name = xenos::GetRegisterName(index);
               XELOGGPU("[%.8X]   %.8X -> %.4X %s",