Boost.Range merge from trunk to release.

This is motivated by the need to correct the istream_range, to correct the adaptors.hpp header file, and correct the return types of various range algorithms.

[SVN r61517]

libs/range

@@ -1 +1 @@
-Subproject commit dfc30e334dfa96bb21ddbaf10087afda586e6dc6
+Subproject commit a47f15a98fe609d701c4d034cf116cb03612d202