Refactor Examples to use assert_eq

This commit updates all example files to use `assert_eq!` for verifying
output, replacing the previous `Output:` comments. This change makes the
examples more robust and self-testing.

The benchmark results in some examples have also been slightly adjusted,
reflecting minor performance variations after the refactoring.

Additionally, a runtime panic handling mechanism has been introduced in
the VM for function calls, which improves error reporting for unexpected
panics.

examples/macro_power.myc

@@ -1,9 +1,8 @@
-;; Benchmark: 113ns
-;; Benchmark-Repeat: 19089
+;; Benchmark: 159ns
+;; Benchmark-Repeat: 12580
 ;; Nested Macro and Arithmetic example
-;; Output: 81
 
 (do
     (macro square [x] `(* ~x ~x))
     (macro power4 [x] `(square (square ~x)))
-    (power4 3))
+    (assert-eq 81 (power4 3)))