Options for select fields

As it is right now, the placeholder value for

<select>

fields is hardcoded in

geodir_cfi_select()

.
It would be nice if this could use the configured placeholder value if it is set.

Furthermore, it is not possible to revert a selection once it has been made. It would be nice if

data-allow-clear="true"

could be set for non-required fields, maybe only if enabled via a new setting?

Last but not least, for single <select> fields an initial empty option is missing so the first option is always selected by default.
This might make sense in some cases (those can already be handled by explicitly setting the default value), in others it does not.
It would therefore be nice if an empty option could be displayed in case a default option is not set