* Style and Rule now have separate context properties

* new convenience method addUniqueValueRules in OL.!StyleMap. This can actually be used to achieve what I was trying to show in the example of this ticket's description.
 * some refactoring of OL.Style to remove duplicate code (with tests)
 * a new example showing how to add a "unique value" legend to a point layer using the new addUniqueValueRules method
 * Rule.symbolizer can now also be just a symbolizer, instead of a hash of symbolizers keyed by "Point", "Line", "Polygon". This will make things even simpler (as can be seen in the styles-unique.html example)

r=tschaub (closes #1373)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@6396 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

tests/Rule/test_Comparison.html

@@ -38,7 +38,7 @@
     }
     
     function test_Comparison_evaluate(t) {
-        t.plan(3);
+        t.plan(4);
         
         var rule = new OpenLayers.Rule.Comparison({
                 property: "area",
@@ -62,6 +62,11 @@
             t.eq(result, ruleResults[i], "feature "+i+
                     " evaluates to "+result.toString()+" correctly.");
         }
+        rule.context = {
+            area: 4998
+        }
+        var result = rule.evaluate();
+        t.eq(result, true, "evaluation against custom rule context works.");
     }
     </script> 
 </head>