Merge branch 'devs/bdilly/edje_multiseat'

This series implement multiseat support on Edje:
 * emit signals with seat name as suffix
 * handle multiseat focus
 * add optional argument to FOCUS_SET and FOCUS_OBJECT actions
   to specify a seat
 * add Edje naming for seats (incremental) with flag
   to disable this behaviour - so custom (evas) names will be used
 * add 3 examples exploring all these new features

Reviewed By: cedric, iscaro, jpeg

Differential Revision: https://phab.enlightenment.org/D4451

@feature