Add a simple repo-checking tool

It is superset of tests, testing repository itself, not only the code.

repocheck.sh

@@ -0,0 +1,38 @@
+#!/bin/sh
+
+# SPDX-FileCopyrightText: 2022 LEdoian <checklib@pokemon.ledoian.cz>
+# SPDX-License-Identifier: CC0-1.0
+
+# This is a simple script to check correctness/compliance of the repository as
+# a whole. This is different from tests (test.py), which deal only with
+# corectness of the code. This also checks the code using other tools, which do
+# not directly impact the code, but try to minimize technical debt.
+
+# I know that there are more sophisticated tools. This seemed sufficient and
+# lightweight enough, so I didn't look further. You can try to convince me
+# otherwise, please write me an email.
+
+set -e
+
+red() {
+	tput setaf 1
+	echo "$@"
+	tput sgr0
+}
+
+has_reuse=$(type reuse >/dev/null 2>&1 && echo true || echo false)
+if $has_reuse; then
+	reuse lint
+else
+	red "REUSE tool not found, skipping"
+fi
+
+
+has_mypy=$(type mypy >/dev/null 2>&1 && echo true || echo false)
+if $has_mypy; then
+	mypy *.py
+else
+	red "Mypy not found, skipping"
+fi
+
+./test.py