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.party.h

@@ -1,6 +1,6 @@
 class cDialog;
-void init_party(short mode) __attribute__((deprecated));
-void init_party_scen_data() __attribute__((deprecated));
+__declspec(deprecated) void init_party(short mode);
+__declspec(deprecated) void init_party_scen_data();
 void make_boats();
 bool create_pc(short spot,cDialog* parent_num);
 bool take_sp(short pc_num,short amt);