ContainsNoCase

Extension for Contains() used extensively, here as `ContainsNoCase` for indexOf() with StringComparison type options: 

CurrentCulture, CurrentCultureIgnoreCase, InvariantCulture, InvariantCultureIgnoreCase, Ordinal, OrdinalIgnoreCase

The extension here implements the String.IndexOf Method (String,StringComparison) method: 
https://msdn.microsoft.com/en-us/library/ms224425(v=vs.110).aspx

Allows clean access to this method as `ContainsNoCase(string, StringComparison.TYPE)`

src/NadekoBot/_Extensions/Extensions.cs

@@ -278,6 +278,15 @@ namespace NadekoBot.Extensions
                 return list;
             }
         }
+    
+        /// <summary>
+        /// Easy use of fast, efficient case-insensitive Contains check with StringComparison Member Types 
+        /// CurrentCulture, CurrentCultureIgnoreCase, InvariantCulture, InvariantCultureIgnoreCase, Ordinal, OrdinalIgnoreCase
+        /// </summary>    
+        public static bool ContainsNoCase(this string str, string contains, StringComparison compare)
+        {
+            return str.IndexOf(contains, compare) >= 0;
+        }
 
         public static string TrimTo(this string str, int maxLength, bool hideDots = false)
         {
@@ -436,4 +445,4 @@ namespace NadekoBot.Extensions
                     : usr.AvatarUrl;
         }
     }
-}
+}