Add a "refresh" method in server side

e only way that I know, is by press the refresh button in GTK client or use a "on_change" call.

If we do some changes in database and we need to refresh the on screen data, we need to send the "refresh" button commad to server.

I think that is necesary to add a refresh method who can called from module code (_refresh_view).

sample code (not real case):

# whe create (by code) any invoice line
self.pool.get('account.invoice').write(cr, uid, id, {'invoice_line':(0,0,any_line)}, context=ctx)
self.pool.get('account.invoice')._refresh_view(cr, uid, id) # == press "Refresh" Button