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/Entity.h

@@ -8,8 +8,6 @@
 #include <vector>
 #include <string>
 
-#define		rn( rx,  ry) ((rx) + ((ry) * 100))
-
 enum
 {
     BLOCK = 0,
@@ -82,8 +80,6 @@ public:
 
     int crewcolour(int t);
 
-    void setenemyroom(int t, int rx, int ry);
-
     void settreadmillcolour(int t, int rx, int ry);
 
     void createentity(float xp, float yp, int t, float vx = 0, float vy = 0,