[Positioner] PosUtil::is_in_interval(): bound == 0

PosUtil::is_in_interval() now handles a zero interval width. That is
required in case of standard deviation equals to zero.

owlps-positioner/src/posutil.hh

@@ -74,6 +74,9 @@ public:
 inline bool PosUtil::
 is_in_interval(float center, float bound, float value)
 {
+  if (bound == 0)
+    return value == center ;
+
   assert(bound > 0) ;
   float interval_min = center - bound ;
   float interval_max = center + bound ;