Added a blinking icon to force_encounter/with_flags functions

* currently an icon is always shown for scripted force encounters.

artifacts/scripting/headers/lib.math.h

@@ -11,7 +11,7 @@
 #define below_equal(a, b)  (unsigned_comp(a, b) <= 0)
 
 procedure unsigned_comp(variable a, variable b) begin
-   if (a bwxor b) then return 0;
+   if ((a bwxor b) == 0) then return 0; // a == b
    if (b == 0) then return 1;
    return 1 if (a / b) else -1;
 end

artifacts/scripting/headers/sfall.h

@@ -80,6 +80,7 @@
 //Valid flags for force_encounter_with_flags
 #define ENCOUNTER_FLAG_NO_CAR   (1)
 #define ENCOUNTER_FLAG_LOCK     (2) // block new forced encounter by the next function call until the current specified encounter occurs
+#define ENCOUNTER_FLAG_SPECIAL  (4) // special blinking icon
 
 //The attack types returned by get_attack_type
 #define ATKTYPE_LWEP1           (0)