Add calculate callback to Evas_Smart_Class.

Add calculate callback to Evas_Smart_Class.

Some people is using it for some time now without problems, so I'm
adding it to SVN to get some broader use. Remember to recompile ALL
libraries that depend on Evas as it will change the
EVAS_SMART_CLASS_VERSION and old classes will fail to load.

This will also change Edje so it will postpone _edje_recalc() to
render time, calculate() callback, however some methods will force
early recalculation.

git-svn-id: svn+ssh://svn.enlightenment.org/var/svn/e/trunk/evas@35860 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33