Add new view type: listform

As per: https://discuss.tryton.org/t/forms-in-listview/1053

assigned to @nicoe

added sao tryton trytond type::feature + 1 deleted label

review255091002 updated at https://codereview.tryton.org/255091002/#ps253091002

added 1 deleted label and removed 1 deleted label

review255091002 updated at https://codereview.tryton.org/255091002/#ps279071003

review255091002 updated at https://codereview.tryton.org/255091002/#ps255131002

review255091002 updated at https://codereview.tryton.org/255091002/#ps281101002

review255091002 updated at https://codereview.tryton.org/255091002/#ps249111002

review255091002 updated at https://codereview.tryton.org/255091002/#ps253121002

review255091002 updated at https://codereview.tryton.org/255091002/#ps269141002

review255091002 updated at https://codereview.tryton.org/255091002/#ps261101002

review255091002 updated at https://codereview.tryton.org/255091002/#ps273111002

review255091002 updated at https://codereview.tryton.org/255091002/#ps277161003

review255091002 updated at https://codereview.tryton.org/255091002/#ps261211002

review255091002 updated at https://codereview.tryton.org/255091002/#ps265191008

review255091002 updated at https://codereview.tryton.org/255091002/#ps251201002

review255091002 updated at https://codereview.tryton.org/255091002/#ps287241002

review255091002 updated at https://codereview.tryton.org/255091002/#ps253281002

review255091002 updated at https://codereview.tryton.org/255091002/#ps275201002

review255091002 updated at https://codereview.tryton.org/255091002/#ps271211002