Add very basic test framework for parser tests.

Start with a shell script that runs .cton files through 'cton-util cat' and
compares the output to a reference. This can get fancy later.

tests/parser/run.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+
+# Go to tests directory.
+cd $(dirname "$0")/..
+
+# The path to cton-util should be in $CTONUTIL.
+if [ -z "$CTONUTIL" ]; then
+    CTONUTIL=../src/tools/target/debug/cton-util
+fi
+
+if [ ! -x "$CTONUTIL" ]; then
+    echo "Can't fund executable cton-util: $CTONUTIL" 1>&2
+    exit 1
+fi
+
+declare -a fails
+
+for testcase in $(find parser -name '*.cton'); do
+    ref="${testcase}.ref"
+    if [ ! -r "$ref" ]; then
+        fails=(${fails[@]} "$testcase")
+        echo MISSING: $ref
+    elif diff -u "$ref" <("$CTONUTIL" cat "$testcase"); then
+        echo OK $testcase
+    else
+        fails=(${fails[@]} "$testcase")
+        echo FAIL $testcase
+    fi
+done
+
+if [ ${#fails[@]} -ne 0 ]; then
+    echo
+    echo Failures:
+    for f in "${fails[@]}"; do
+        echo "  $f"
+    done
+    exit 1
+else
+    echo "All passed"
+fi