This only adds the tree creation functions, no sorting and name mangling
yet. Only plain ECMA-119 supported for now, nor RR, relaxed
restrictions, etc..
This also adds a little test program.
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.
