Add .gitignore

.gitignore

@@ -138,3 +138,14 @@ __pycache__
 *_source.tar.bz2
 snap/.snapcraft
 tcp-proxy/tcp-proxy
+
+# Generated by Cargo
+# Compiled files, executables, and build artifacts
+rustybits/
+/target/
+
+# Backup files generated by rustfmt
+**/*.rs.bk
+
+# MSVC Windows builds generate these for debugging
+*.pdb