all expr types have nested ::id, add deep_copy() for storing all nodes by value, and BOOST_PROTO_AUTO(var, expr) as a shortcut for BOOST_AUTO(var, proto::deep_copy(expr))

[SVN r36134]

libs/xpressive

@@ -1 +1 @@
-Subproject commit 859862c1b3df2a4c09df784a702fe8c7a7793f8c
+Subproject commit 26f5383d574fd2f079fe6a9149f09e760351b42d