cast operator name for insensitive compatibility

Author: Pierozi

Test/Integration/Model/Operator.php

@@ -204,4 +204,30 @@ function ($b) use (&$gExecuted) {
                 ->boolean($gExecuted)
                     ->isTrue();
     }
+    
+    public function case_insensitive()
+    {
+        $this
+            ->given(
+                $ruler = new LUT(),
+                $asserter  = $ruler->getDefaultAsserter(),
+                $asserter->setOperator(
+                    'myFirstMethod',
+                    function () { return true; }
+                ),
+                $asserter->setOperator(
+                    'mySecondMethod',
+                    function () { return true; }
+                ),
+                $asserter->setOperator(
+                    'mythirdmethod',
+                    function () { return true; }
+                ),
+                $rule = 'myFirstMethod() and mysecondmethod() and myThirdMethod()'
+            )
+            ->when($result = $ruler->assert($rule, new LUT\Context()))
+            ->then
+                ->boolean($result)
+                    ->isTrue();
+    }
 }

Visitor/Asserter.php

@@ -465,7 +465,7 @@ public function getContext()
      */
     public function setOperator($operator, $callable)
     {
-        $this->_operators[$operator] = $callable;
+        $this->_operators[mb_strtolower($operator)] = $callable;
 
         return $this;
     }