Remove unused function entityclass::resetflags()

This looks like a weird hack, but there's no way a flag will ever end up
being 2, not even before I changed all flags to be bools instead.

desktop_version/src/Entity.h

@@ -28,8 +28,6 @@ public:
 
     void resetallflags();
 
-    void resetflags();
-
     void confirmflags();
 
     void fatal_top()