Remove staticmethod decorator on method to define key to group purchases

method _group_purchase_key in CreatePurchase wizard is defined as staticmethod but should not.

added purchasing + 1 deleted label

added easy type::feature labels

assigned to @udono

added 1 deleted label and removed 1 deleted label

New changeset 1b538e99e5c9 by Udo Spallek in branch 'default':
Change staticmethod to classmethod
https://hg.tryton.org/modules/purchase_request/rev/1b538e99e5c9

added 1 deleted label and removed 1 deleted label

closed

New changeset 60126a09ac34 by Cédric Krier in branch 'default':
Change staticmethod to classmethod
https://hg.tryton.org/tryton-env/rev/60126a09ac34