Tidy up theme setting logic when some settings do not exist.  Fix enablecustomlogin logic to be the default when the setting is unknown.

Hi Julian,

Slight tidy up to reduce logic as in PHP the second test in an 'AND' comparison is not evaluated if the first is false.  Hence no problem if the setting does not exist.

Also changed the logic of enablecustomlogin such that the default will happen if the setting is not there,

Cheers,

Gareth