Allow case insensitive not equals operator

README.md

@@ -192,6 +192,7 @@ You can replace this DSL with your own (eg. use JSON instead) by implementing an
 | `@=*`      | Case-insensitive string Contains |
 | `_=*`      | Case-insensitive string Starts with |
 | `==*`      | Case-insensitive string Equals |
+| `!=*`      | Case-insensitive string Not equals |
 | `!@=*`     | Case-insensitive string does not Contains |
 | `!_=*`     | Case-insensitive string does not Starts with |
 

Sieve/Models/FilterTerm.cs

@@ -13,6 +13,7 @@ namespace Sieve.Models
         private static readonly string[] Operators = new string[] {
                     "!@=*",
                     "!_=*",
+                    "!=*",
                     "!@=",
                     "!_=",
                     "==*",

SieveUnitTests/General.cs

@@ -96,6 +96,20 @@ namespace SieveUnitTests
             Assert.IsTrue(result.Count() == 1);
         }
 
+        [TestMethod]
+        public void NotEqualsCanBeCaseInsensitive()
+        {
+            var model = new SieveModel()
+            {
+                Filters = "Title!=*a"
+            };
+
+            var result = _processor.Apply(model, _posts);
+
+            Assert.AreEqual(result.First().Id, 1);
+            Assert.IsTrue(result.Count() == 3);
+        }
+
         [TestMethod]
         public void ContainsIsCaseSensitive()
         {