Add interface for comparison of ws_object instances
Add compare callback for object type
Add stub for ws_object_cmp()
Add implementation of ws_object_cmp()
Add compare callback for ws_wayland_obj
Use the ws_object_cmp() function in the compare callback for the libreset interface
Merge pull request #132 from matthiasbeyer/add-obj_cmp

Add object compare mechanism
Added ws_object_attribute type
Added example object attribute table
Add ws_object_attr() for getting attrs inclusive stub
Add implementation for ws_object_attr_read()
Add function for getting the type of an attribute (and stub)
Add implementation of ws_object_attr_type()