mergesort.rs: add (with commented out debug prints)
mergesort.rs: remove debug printlns
mergesort.rs: cleanup and add some assertions
mergesort.rs: make the code slightly more idiomatic
mergesort.rs: pass by mutable reference
mergesort.rs: make even more "rusty"
mergesort.rs: use u8s instead of ints
mergesort.rs: add main for sorting a real file
mergesort.rs: convert to generics