MultipleDataForm should not init Node twice

[misc]

goto in src/ , run python

import common.i18n import common.dataforms print common.dataforms.MultipleDataForm?('submit')

<tag />

with the following patch :

import common.i18n import common.dataforms print common.dataforms.MultipleDataForm?('submit')

<x xmlns="jabber:x:data" type="submit" />

[misc]

remove the code to initialise twice the node, as DataForm? already does it

[steve-e]

(In [8259]) [misc] init Node in MultipleDataForm? only once. Fixes #3228

[asterix]

(In [8679]) [misc] init Node in MultipleDataForm?? only once. Fixes #3228