Further header & precompiled cleanup, fix no-PCH builds.

GUIObjectBase is made a IGUIObject* to avoid including those headers
un-necessarily. Subsequent diffs ought to clean up the various of
pointers for that with a similar type with reference semantics.

Also:
- Add standard C and C++ headers (mostly cstring for memcpy, string and
vector) where needed.
- Swap out some includes for forward declarations
- Clean up un-necessary boost includes in precompiled and other headers.
- Clean up precompiled headers, including fewer things.
- Move ACPI to the windows-specific folder as it's included there only
and mostly specific to that platform.

Thanks Stan for the testing.

Differential Revision: https://code.wildfiregames.com/D3129
This was SVN commit r24352.

source/ps/scripting/JSInterface_Debug.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2019 Wildfire Games.
+/* Copyright (C) 2020 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -24,6 +24,7 @@
 #include "lib/debug.h"
 #include "scriptinterface/ScriptInterface.h"
 
+#include <ctime>
 #include <string>
 
 /**