(main): Removed the 'c' command since l2g_compact no longer exists.
Added the 'i' command that tests iterators. Adjusted to the new API of l2g_dump, l2g_read and l2g_write. Require an extra trailing newline after the representation l2g_read expects when the 'r' command is used, and produce a corresponding newline with the 'w' command. Renamed the 'p' command to 'w'.