Reverted resource references for combine_something, you can't use tool_image here, because on MSW that only works for .bmps'

Added dependency stuff to invalidate Choice images;
Fixed 'duplicate' in symbol editor

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@197 0fc631ac-6414-0410-93d0-97cfa31319b6

src/script/image.hpp

@@ -71,6 +71,10 @@ class ScriptableImage {
 	inline void initDependencies(Context& ctx, const Dependency& dep) const {
 		script.initDependencies(ctx, dep);
 	}
+	/// Invalidate the cached image
+	inline void invalidate() {
+		cache = ScriptImageP();
+	}
 	
   private:
 	OptionalScript script;		///< The script, not really optional