Improve exception dumps and general debug info, make the emulator capable of running the riscv ISA tests, and perform some general fixes i found while making it pass the tests for RV64I

src/decode.rs

@@ -6,9 +6,15 @@
 
 const MASK_REGISTER: u32 = 0x1f;
 
-#[derive(Debug, Clone, Copy)]
+#[derive(Clone, Copy)]
 pub struct Instruction(pub u32);
 
+impl std::fmt::Debug for Instruction {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_fmt(format_args!("{:08x}", self.0))
+    }
+}
+
 #[allow(dead_code)]
 impl Instruction {
     #[inline]