Automatic merge from submit-queue

SetSelfLink is inefficient

Generating self links, especially for lists, is inefficient.  Replace
use of net.URL.String() call with direct encoding that reduces number of
allocations. Switch from calling meta.ExtractList|SetList to a function
that iterates over each object in the list.

In steady state for nodes performing frequently small get/list
operations, and for larger LISTs significantly reduces CPU and
allocations.

@wojtek-t this is the next big chunk of CPU use during the large N nodes simulation test (11% of master CPU). Takes a few allocations out of the critical path