add a test that would fail with the restricted whitelist approach

If no option is set, valid genres should not be rejected. Which is an argument
to have a wide default whitelist.
Merge branch 'KraYmer-lastgenre-tests-new' into lastgenre-tests-new

Conflicts:
	test/test_lastgenre.py
lastgenre: Restore default whitelist
use booleans for whitelist and c14n options

homogenise options setup using booleans, while keeping the empty string
(synonym of ‘true’) for backward compatibility.