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/util/age.hpp

@@ -23,6 +23,11 @@ class Age {
 	Age() {
 		update();
 	}
+	/// Create a special age
+	/** 0: dummy value, used for other purposes
+	 *  1: before 'beginning of time', the age conceptually just before program start
+	 *  2..: normal ages
+	 */
 	Age(AtomicIntEquiv age) : age(age) {}
 	
 	/// Update the age to become the newest one