Implement function to recursively add a dir to an iso tree.

This commit also to the following changes:
- create_node() on builder never frees the IsoFileSource, it is responsability 
  of the caller to free it.
- Recursive addition options added to IsoImage (not exposed to public API yet)
- create_node() takes care about follow_symlinks
- Added little demo program to test it.

src/image.h

@@ -21,6 +21,8 @@
  * (Usefull, for example, in Multiple-Document-Interface GUI apps.
  * [The stuff we have in init belongs really to image!]
  */
+ 
+typedef struct Iso_Image_Rec_Opts IsoImageRecOpts;
 
 struct Iso_Image {
 	
@@ -51,6 +53,68 @@ struct Iso_Image {
      * Default builder to use when adding files to the image tree.
      */
     IsoNodeBuilder *builder;
+    
+    /**
+     * Options for recursive directory addition
+     */
+    IsoImageRecOpts *recOpts;
+};
+
+/**
+ * Options for recursive directory addition
+ */
+struct Iso_Image_Rec_Opts {
+    
+    /**
+     * Whether to follow symlinks or just add them as symlinks
+     */
+    unsigned int follow_symlinks;
+    
+    /**
+     * Whether to skip hidden files
+     */
+    unsigned int ignore_hidden;
+    
+    /**
+     * Whether to stop on an error. Some errors, such as memory errors,
+     * always cause a stop
+     */
+    unsigned int stop_on_error;
+    
+    /**
+     * Files to exclude
+     * TODO add wildcard support
+     */
+    char** excludes;
+    
+    /**
+     * if the dir already contains a node with the same name, whether to
+     * replace or not the old node with the new. 
+     *      - 0 not replace
+     *      - 1 replace 
+     *      TODO #00006 define more values
+     *          to replace only if both are the same kind of file
+     *          if both are dirs, add contents (and what to do with conflicts?)
+     */
+    int replace;
+    
+    /**
+     * When this is not NULL, it is a pointer to a function that will
+     * be called just before a file will be added, or when an error occurs.
+     * You can overwrite some of the above options by returning suitable 
+     * values.
+     * 
+     * @param action
+     *      1 file will be added
+     *      2 file will be skipped
+     *      < 0 error adding file (return 3 to stop, 1 to continue)
+     * @param flag
+     *      0 no problem
+     *      1 file with same name already exists
+     * @return
+     *      1 add/continue, 2 skip, 3 stop
+     */
+    int (*report)(IsoFileSource *src, int action, int flag);
 };
 
 #endif /*LIBISO_IMAGE_H_*/