style(clippy): disallow panics under kindelia/src

Addressing issue kindelia#247.

This causes clippy to emit an error if unwrap, expect, or panic is
used in any code invoked by kindelia/src/main.rs

test cases are not affected.  (panics are allowed)

kindelia/src/main.rs

@@ -1,3 +1,10 @@
+// High assurance software should not panic.
+// We flip the clippy default to deny, so you should think very
+// carefully. If you absolutely cannot avoid it then it has to
+// be explicitly allowed with #[allow(clippy::x)]
+// See https://github.com/Kindelia/Kindelia-Chain/issues/247
+#![warn(clippy::unwrap_used, clippy::expect_used, clippy::panic)]
+
 mod cli;
 mod config;
 mod files;