Multiple string selection for fieldsets, readonly for textboxes with #, class for submit buttons

[hfr]

This are a couple of minor improvements

The value which is used to control the visibility of fieldsets is now a list of strings separated by a '|'.

So the following is possible:

select "label" "A|B|C|D"
fieldset "" "label "A|C"
...

The fieldset will be shown if A or C is selected.

The # is supported as the readonly option. It is currently implemented for textboxes.

Submit buttons support now the .class option, which allows to assign a classname to them. This allows an easier formatting via css.

A configuration field is added to limit the use of forms to specific namespaces. This prevents that users can simply copy forms to different namespaces and use them there. This might be especially important if a different virtual user is used to execute forms.

An additional script interface was added to forward the $argv array to the script. This allows to specify additional parameter when the script is used in the forms.