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

run-riscv-tests.sh

@@ -0,0 +1,12 @@
+#!/bin/bash
+
+for f in $(cat torun.txt); do
+    result=$(cargo run $f 2>&1 | tail -n 1 | awk '{print $NF}')
+    if [[ $result != 0 ]]; then
+        testnum=$(( result >> 1 ))
+        echo $f: test $testnum failed
+        exit 1
+    fi
+done
+
+echo all tests passed