Add Evas Clipped Smart Object.

Add Evas Clipped Smart Object.

This class covers the most common cases, usually its sub-classes will
have to implement resize and override one or two methods at most,
making the smart object usage less error prone and easier.

Default behavior is:
 - add: creates a hidden clipper with "infinite" size;
 - del: delete all children objects;
 - move: move all objects relative relatively;
 - resize: not defined;
 - show: if there are children objects, show clipper;
 - hide: hides clipper;
 - color_set: set the color of clipper;
 - clip_set: set clipper of clipper;
 - clip_unset: unset the clipper of clipper;

Documentation explains an easy way to inherit from this class and
still be able to use overridden methods.

git-svn-id: svn+ssh://svn.enlightenment.org/var/svn/e/trunk/evas@35861 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33