Store joliet-related info in Ecma119Image target insted of Writer.

In fact, this is not a good decission, writer is a better place for 
writer dependent data, but for now I prefer to store anything in the 
target. Later we can improve Writer encapsulation.

src/joliet.h

@@ -17,8 +17,6 @@
 #include "libisofs.h"
 #include "ecma119.h"
 
-typedef struct joliet_node JolietNode;
-
 enum joliet_node_type {
 	JOLIET_FILE,
 	JOLIET_DIR