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/UtilityClass.h

@@ -44,7 +44,7 @@ bool endsWith(const std::string& str, const std::string& suffix);
 class UtilityClass
 {
 public:
-    UtilityClass();
+    UtilityClass(void);
 
     static std::string String(int _v);
 
@@ -61,7 +61,7 @@ public:
 
     static bool intersects( SDL_Rect A, SDL_Rect B );
 
-    void updateglow();
+    void updateglow(void);
 
     int glow;
     int slowsine;