Force display of Many2Many screen after edition

Since changeset 0c2f313bf62d, the cancel of the record is not enough to refresh
the display of the edited record in the Many2Many list view. So a display call
must be triggered to clear the CellCache.

issue4391
review6721002

--HG--
extra : rebase_source : 65dcf0179888d3c0e15ce9e28f7a7a73080a52c9
Allow domain inversion to set None to X2M field

When domain is like ('field', '=', None), the domain inversion set the value to
None.

issue4301
review10701002
Don't fail while autodetecting invalid field in import window

on_row_expanded could be called on node without children by sig_autodetect, in
such case the returned child is an invalid GtkTreeIter. So it must ignore such
case to let sig_autodetect popup an error message.

issue4313
review7791002
Quote search text from widgets

The text set as search_filter from a widget should be quoted to have the same
behavior as the completion and also allow strict matching for text containing
spaces.

issue4388
review10661002
Activate SO_KEEPALIVE on socket

issue4398
review7781003