Summary:
Send order signals for changing item's state according to its order.
It does not affect to existing themes. It sends the following signals.
elm,order,first,item
elm,order,default,item
elm,order,last,item
@feature
Test Plan: N/A
Reviewers: woohyun, jaehwan, eagleeye, cedric
Subscribers: cedric, jpeg
Differential Revision: https://phab.enlightenment.org/D3883