Generalize ZRANGE and ANGRANGE to accept any nonnegative number.

Numbers 0 and 1 mean 'no spread', but the latter does one krand() call.
Negative numbers are reserved for potential future use.

git-svn-id: https://svn.eduke32.com/eduke32@3715 1a8010ca-5511-0410-912e-c29ae57300e0

polymer/eduke32/source/actors.c

@@ -3294,6 +3294,8 @@ static void P_FinishWaterChange(int32_t j, DukePlayer_t *ps, int32_t sectlotag,
         }
 }
 
+// Check prevention of teleportation *when alive*. For example, commanders and
+// octabrains would be transported by SE7 (both water and normal) only if dead.
 static int32_t A_CheckNonTeleporting(int32_t s)
 {
     int32_t pic = sprite[s].picnum;

polymer/eduke32/source/player.c

@@ -434,9 +434,11 @@ static void Proj_MaybeAddSpread(int32_t not_accurate_p, int32_t *zvel, int16_t *
 {
     if (not_accurate_p)
     {
-        // NOTE: if {z,ang}Range is 0, there is a huge spread
-        *zvel += (zRange/2)-(krand()&(zRange-1));
-        *sa += (angRange/2)-(krand()&(angRange-1));
+        // Ranges <= 1 mean no spread at all. A range of 1 calls krand() though.
+        if (zRange > 0)
+            *zvel += zRange/2 - krand()%zRange;
+        if (angRange > 0)
+            *sa += angRange/2 - krand()%angRange;
     }
 }