box: Fix a memory leak of sample description destructors.
read: Set destructor of binary coded box properly.

This fix a memory leak.
box: Fix a memory leak of trak destructor.
box: Merge the common processes at box destruction into a function.
box: Do common box destruction within isom_remove_extension_box().
box: Fix a memory leak of file destructor.
read|print: Fix a memory leak of box absent in ROOT when the dump is disabled.
Implementation of referencing external media files.