add Justfile to execute typical (cargo) commands

Justfile

@@ -0,0 +1,11 @@
+# run tests/checks that are also run by github actions
+ci:
+    cargo fmt --all -- --check
+    cargo check --tests --examples
+    cargo test
+    cargo clippy -- -D warnings
+
+# run clippy (from nightly) in pedantic mode, but warnings only
+# you need to install nightly via rustup, e.g.: `rustup toolchain install nightly --component clippy`
+clippy_pedantic:
+    cargo +nightly clippy --all-targets -- -W clippy::pedantic