Move entityclass::setenemyroom() to entclass::setenemyroom()

This moves the setenemyroom() function onto the entity object itself, so
I can more easily change all 'entities[k].' to 'entity.' in
entityclass::createentity() later.

Additionally, I've had to move the rn() macro from Entity.h to Ent.h, or
else entclass::setenemyroom() won't know what it is.

desktop_version/src/Ent.h

@@ -1,6 +1,8 @@
 #ifndef ENT_H
 #define ENT_H
 
+#define		rn( rx,  ry) ((rx) + ((ry) * 100))
+
 class entclass
 {
 public:
@@ -12,6 +14,8 @@ public:
 
     void setenemy(int t);
 
+    void setenemyroom(int rx, int ry);
+
 public:
     //Fundamentals
     bool active, invis;