Remove usages of g_hFrameWindow and g_hInstance from core emulator files. And Resource related Win32 functions. (PR #915)

. Win32Frame: remove WM_USER_RESTART.

source/Speaker.cpp

@@ -103,7 +103,7 @@ static void DisplayBenchmarkResults ()
            TEXT("This benchmark took %u.%02u seconds."),
            (unsigned)(totaltime / 1000),
            (unsigned)((totaltime / 10) % 100));
-  MessageBox(GetFrame().g_hFrameWindow,
+  GetFrame().FrameMessageBox(
              buffer,
              TEXT("Benchmark Results"),
              MB_ICONINFORMATION | MB_SETFOREGROUND);