Replace makefile with pavement file, granting portability on OS X and Windows. Fixes #505.

Makefile

-empty:
-	exit 1
-
-update-vendored:
-	rm -rf pkg_resources/_vendor/packaging*
-	rm -rf pkg_resources/_vendor/six*
-	rm -rf pkg_resources/_vendor/pyparsing*
-	python3 -m pip install -r pkg_resources/_vendor/vendored.txt -t pkg_resources/_vendor/
-	sed -i 's/ \(pyparsing\|six\)/ pkg_resources.extern.\1/' \
-		pkg_resources/_vendor/packaging/*.py
-	rm -rf pkg_resources/_vendor/*.{egg,dist}-info

pavement.py

+import re
+
+from paver.easy import task, path as Path
+import pip
+
+def remove_all(paths):
+	for path in paths:
+		path.rmtree() if path.isdir() else path.remove()
+
+@task
+def update_vendored():
+	vendor = Path('pkg_resources/_vendor')
+	remove_all(vendor.glob('packaging*'))
+	remove_all(vendor.glob('six*'))
+	remove_all(vendor.glob('pyparsing*'))
+	install_args = [
+		'install',
+		'-r', str(vendor/'vendored.txt'),
+		'-t', str(vendor),
+	]
+	pip.main(install_args)
+	packaging = vendor / 'packaging'
+	for file in packaging.glob('*.py'):
+		text = file.text()
+		text = re.sub(r' (pyparsing|six)', r' pkg_resources.extern.\1', text)
+		file.write_text(text)
+	remove_all(vendor.glob('*.dist-info'))
+	remove_all(vendor.glob('*.egg-info'))