Added thread-safety to thumbnail request system.

Marked symbol requests as not being thread-safe.
Added icon to symbol editor
Made *.* actually register on *



git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@407 0fc631ac-6414-0410-93d0-97cfa31319b6

src/script/image.hpp

@@ -45,6 +45,9 @@ class ScriptableImage {
 	inline void initDependencies(Context& ctx, const Dependency& dep) const {
 		script.initDependencies(ctx, dep);
 	}
+
+	/// Can this be safely generated from another thread?
+	bool threadSafe() const {return value->threadSafe();}
 	
   private:
 	OptionalScript  script;		///< The script, not really optional