7.0 improve acc number completion

Improve the matching on acc_number by removing non alpha num characters when querying the res_partner_bank table

Comes from https://code.launchpad.net/~acsone-openerp/banking-addons/bank-statement-reconcile-70-improve-acc-number-completion/+merge/202861
A more or less standar way to call it in other modules has been 'st_line_obj'.