Use the defined constants for monster abilities as much as possible

- New monster ability: radiate blade fields
- Fix permanent martyr's shield giving immunity to fire walls
- Fix paralysis ray giving immunity to ice walls
- All monsters that radiate fields are now immune to the fields they radiate

src/boe.items.cpp

@@ -833,7 +833,7 @@ void set_town_attitude(short lo,short hi,short att) {
 				
 				univ.town.monst[i].mobility = 1;
 				// If a "guard", give a power boost
-				if(univ.scenario.scen_monsters[num].spec_skill == 37) {
+				if(univ.scenario.scen_monsters[num].spec_skill == MONSTER_GUARD) {
 					univ.town.monst[i].active = 2;
 					univ.town.monst[i].health *= 3;
 					univ.town.monst[i].status[eStatus::HASTE_SLOW] = 8;