Explicitly declare void for all void parameter functions (#628)

Apparently in C, if you have `void test();`, it's completely okay to do
`test(2);`. The function will take in the argument, but just discard it
and throw it away. It's like a trash can, and a rude one at that. If you
declare it like `void test(void);`, this is prevented.

This is not a problem in C++ - doing `void test();` and `test(2);` is
guaranteed to result in a compile error (this also means that right now,
at least in all `.cpp` files, nobody is ever calling a void parameter
function with arguments and having their arguments be thrown away).
However, we may not be using C++ in the future, so I just want to lay
down the precedent that if a function takes in no arguments, you must
explicitly declare it as such.

I would've added `-Wstrict-prototypes`, but it produces an annoying
warning message saying it doesn't work in C++ mode if you're compiling
in C++ mode. So it can be added later.

desktop_version/src/Script.h

@@ -20,7 +20,7 @@ class scriptclass
 public:
 
 
-    scriptclass();
+    scriptclass(void);
 
     void load(const std::string& name);
     void loadother(const char* t);
@@ -31,19 +31,19 @@ public:
         commands.push_back(t);
     }
 
-    void clearcustom();
+    void clearcustom(void);
 
     void tokenize(const std::string& t);
 
-    void run();
+    void run(void);
 
-    void resetgametomenu();
+    void resetgametomenu(void);
 
     void startgamemode(int t);
 
-    void teleport();
+    void teleport(void);
 
-    void hardreset();
+    void hardreset(void);
 
     //Script contents
     std::vector<std::string> commands;