Using EntityIndex constant

Author: sschmid

Addons/Entitas.CodeGenerator/Entitas.CodeGenerator/Generators/EntityIndexGenerator.cs

@@ -28,7 +28,7 @@ public static class ContextsExtensions {
 
         const string ADD_INDEX_TEMPLATE =
 @"        ${contextName}.AddEntityIndex(new ${IndexType}<${ContextName}Entity, ${KeyType}>(
-            ""${IndexName}"",
+            ${IndexName},
             ${contextName}.GetGroup(${ContextName}Matcher.${IndexName}),
             (e, c) => { var component = c as ${ComponentType}; return component != null ? component.${MemberName} : e.${componentName}.${MemberName}; }));";