Taxonomy sub-generator doesn't handle - in taxonomy name correctly in test case

[bignall]

When a taxonomy name contains a '-' the taxonomy sub generator doesn't generate the test_class_access() test case correctly. It should convert the '-' to a '_' like it does for the base plugin. For example, with a taxonomy called 'site-type', it generated the following:

    function test_class_access() {
        $this->assertTrue( che()->site-type instanceof CHE_Site_type );
    }

When it should be

    function test_class_access() {
        $this->assertTrue( che()->site_type instanceof CHE_Site_type );
    }