merged from trunk

svn path=/branches/proto/v4/boost/units/; revision=46303
merged from trunk

svn path=/branches/proto/v4/boost/units/; revision=47983
merged from trunk

svn path=/branches/proto/v4/boost/units/; revision=48169
merged from trunk

svn path=/branches/proto/v4/boost/units/; revision=49439
merged from trunk

svn path=/branches/proto/v4/libs/units/; revision=49607