Merged Boost.Graph changes from trunk

svn path=/branches/release/boost/graph/distributed/; revision=80740
Merged Boost.Graph changes from trunk for 1.53

svn path=/branches/release/boost/graph/distributed/; revision=82061
Merged boost::algorithm::gather and updated tests for Utility, Algorithm and Utility libraries

svn path=/branches/release/boost/graph/distributed/; revision=83154
merge [82960] to release, fixes #7663

svn path=/branches/release/boost/graph/distributed/; revision=83381