Expose radius_tmpl_cast() for others to use
Parse values for switch statements

If we're switch over an attribute, check that the values in the
case statements are appropriate for the attribute.
switching over a non-existent attribute jumps to the default

So we don't do any expansions, hostname lookups, etc.
Otherwise if we're switching over an IP address attribute, it
might end up doing a DNS lookup for every 'case' statement
Fix typo
Allow a wider range of attribute comparisons in switch / case

via casting the attribute in the 'case' to the one in the 'switch'