Minimize size of the resulting binary: 834 -> 634 kiB.

--- a/Cargo.toml
+++ b/Cargo.toml
@@ -60,6 +60,9 @@
 # use LTO for smaller binaries (that take longer to build)
 [profile.release]
 lto = true
+codegen-units = 1
+opt-level = "z"
+panic = "abort"
 
 
 [package.metadata.deb]