Track Cargo lockfile in the repository

The main reason for not including one for library crates is because it's
not going to be respected by the final binary or transient library.
However, since we also publish a binary, it's worthwhile to track it
ourselves.

Author: Xanewok

.gitignore

@@ -1,5 +1,4 @@
 target/
 **/*.rs.bk
-Cargo.lock
 *.rlib
 tests/debug.sh