added fast function to ceck for overlapping rectangles

src/slang/geometry/rectangles_overlap.sl

+define rectangles_overlap (src,clp)
+%!%+
+%\function{rectangles_overlap}
+%\synopsis{Checks whether two rectangles overlap}
+%\usage{res=rectangles_overlap(src,clp)}
+%\description
+%
+%This function checks whether the two rectangles src and clp
+%overlap (return value=1) or not (return value =0).
+%
+% The rectangles are defined by (xmin,ymin,xmax,ymax)
+% either as a 4 element array in this order or as a
+% struct with these tags. Both boxes must be defined
+% using the same format.
+%
+%!%-
+{
+    if (typeof(src)!=typeof(clp)) {
+        throw UsageError,"%s: src and clp must have the same type!",_function_name();
+    }
+
+    variable xmin,xmax,ymin,ymax;
+    if (typeof(src)==Array_Type) {
+        %  (sxmax<=cxmin || sxmin>=cxmax)
+        if (src[2]<=clp[0] || src[0]>=clp[2]) {
+            return 0;
+        }
+        
+        % if (symax<=cymin || symin>=cymax)
+        if (src[3]<=clp[1] || src[1]>=clp[3]) {
+            return 0;
+        }
+        return 1;
+    }
+
+    if (src.xmax<=clp.xmin || src.xmin>=clp.xmax) {
+        return 0;
+    }
+        
+    if (src.ymax<=clp.ymin || src.ymin>=clp.ymax) {
+        return 0;
+    }
+
+    return 1;
+
+}