Allow extensions to specify preprocessor directives (#101)

Author: dassjosh

src/Extensions/Extension.cs

@@ -1,4 +1,5 @@
-using System.Linq;
+using System.Collections.Generic;
+using System.Linq;
 using System.Reflection;
 
 namespace Oxide.Core.Extensions
@@ -101,6 +102,15 @@ public virtual void LoadPluginWatchers(string pluginDirectory)
         {
         }
 
+        /// <summary>
+        /// Gets the preprocessor directives for this extension
+        /// </summary>
+        /// <returns></returns>
+        public virtual IEnumerable<string> GetPreprocessorDirectives()
+        {
+            return Enumerable.Empty<string>();
+        }
+
         /// <summary>
         /// Called after all other extensions have been loaded
         /// </summary>