[IMP] etree-ify default view generations
[IMP] etree-ify default view generations

* Search already used etree internally, remove serialization to string
* form and tree were easy to convert
* pull down fvg's parsing (etree.fromstring) into calendar generator before converting it

akretion/openerp-server,akretion/openerp-server,akretion/openerp-server