ess.TraceWin.project remove dbg print, cleaning

ess/TraceWin.py

@@ -1594,13 +1594,11 @@ class project:
         self._dict[parameter] = value
 
     def _check_rule_same_sign(self, variables, explanation, fail_on_err):
-        import numpy
 
-        s1 = numpy.sign(self.get(variables[0]))
+        v1 = self.get(variables[0])
         for i in range(1, len(variables)):
-            s2 = numpy.sign(self.get(variables[i]))
-            print("DBG", s1, s2)
-            if s1 != s2:
+            v2 = self.get(variables[i])
+            if abs(v1 + v2) != abs(v1) + abs(v2):
                 errmsg = f"{variables[i]} and {variables[0]} have opposite signs\nExplanation/logic: {explanation}"
                 if fail_on_err:
                     raise ValueError(errmsg)