lib/codegen-meta moved into lib/codegen. (#423)

* lib/codegen-meta moved into lib/codegen.

* Renamed codegen-meta and existing meta.

lib/codegen/meta-python/check.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+set -euo pipefail
+topdir=$(dirname "$0")
+cd "$topdir"
+
+function runif {
+    if type "$1" > /dev/null 2>&1; then
+        version=$("$1" --version 2>&1)
+        echo "   === $1: $version ==="
+        "$@"
+    else
+        echo "$1 not found"
+    fi
+}
+
+# Style linting.
+runif flake8 .
+
+# Type checking.
+runif mypy --py2 build.py
+
+# Python unit tests.
+runif python2.7 -m unittest discover
+
+# Then run the unit tests again with Python 3.
+# We get deprecation warnings about assertRaisesRegexp which was renamed in
+# Python 3, but there doesn't seem to be an easy workaround.
+runif python3 -Wignore:Deprecation -m unittest discover