Isolate JKRHeap operator overloads

Fixes #25

This isolates the JKRHeap operator new/delete overloads. Every single new/delete site in the code has been replaced with a macro.

Sadly for new[] and delete[] we have to keep global operators. The global new[] just allocates into malloc() however, and delete[] goes into free() if it's not in a JKRHeap. So that's fine.

src/d/d_menu_quit.cpp

@@ -25,8 +25,8 @@ dMenu_Quit_c::dMenu_Quit_c() {
 }
 
 dMenu_Quit_c::~dMenu_Quit_c() {
-    delete mStick;
-    delete mpScrnExplain;
+    JKR_DELETE(mStick);
+    JKR_DELETE(mpScrnExplain);
     mpScrnExplain = NULL;
 }