Eliminate use of __attribute__

Ideally this would be standard C++, but here I've settled for things that should be supported by both clang and VS/cl.exe:
- Deprecated attribute retained, but now uses __declspec syntax
- Packed attribute replaced with pragma pack, except one instance where it unnecessary
- Aligned attribute replaced with explicit padding bytes inserted in the structs where needed
- Unused attribute simply removed (though where possible, the unused entities were also removed)

osx/boe.main.cpp

@@ -148,6 +148,10 @@ void check_for_intel();
 bool mac_is_intel;
 
 int main(int argc, char* argv[]) {
+#if 0
+	void debug_oldstructs();
+	debug_oldstructs();
+#endif
 	try{
 		init_directories(argv[0]);
 		//data_store = (piles_of_stuff_dumping_type *) NewPtr(sizeof(piles_of_stuff_dumping_type));