[thin_dump (rust)] First pass at thin_dump.

Doesn't include --repair.

This includes <def> and <ref> sections for shared regions.

src/thin/mod.rs

@@ -2,4 +2,5 @@ pub mod block_time;
 pub mod device_detail;
 pub mod superblock;
 pub mod check;
+pub mod dump;
 pub mod xml;