Merge branch 'devs/bdilly/edje_multiseat_filter'

Merge branch 'devs/bdilly/edje_multiseat_filter'

This series add support to filter events per seat
on edje parts.
With the flag allowed_seats the developer may choose which
seats are allowed to input each part.

Also it adds functions to embryo to set/unset focus, since
it's relevant when writting multiseat applications with
dynamic seats (not fixed number of seats). Seats are
optional arguments on such functions.

Reviewed By: iscaro

Differential Revision: https://phab.enlightenment.org/D4499

@feature