accessibility: ATSPI2 support.

accessibility: ATSPI2 support.

Summary:
Hello guys,

Below You can find a proof o concept for ATSPI2 support for elementary applications. Currently application can only be listed on bus by clients such as 'accersiser'. I am strongly looking for comments to this design.

Here are my comment regarding following code:
* This pach requires https://phab.enlightenment.org/D327 patch to compile
* I have decided to include whole atspi-constants header, because in fact i will need one-to-one copy of all its enums and defines. Qt has something like 3rdparty folder from which they include this header and don't require atspi dev packages at compilation time. Maybe efl needs the same solution or should just require next package in compilation? I agree that putting atspi-constant.h in main source tree is bad idea, but where? src/utils ??

Reviewers: cedric, raster, kimcinoo

Reviewed By: raster

CC: pkaczmarek-samsung, seoz, jaehwan, kimcinoo
Differential Revision: https://phab.enlightenment.org/D328