Change detail namespace.

Big search and replace to change name of internal namepace so it's mangled with the Boost version number - the aim is to reduce the chances of mixing different header and library versions.

include/boost/regex/v4/mem_block_cache.hpp

@@ -28,7 +28,7 @@
 #endif
 
 namespace boost{
-namespace re_detail{
+namespace BOOST_REGEX_DETAIL_NS{
 
 struct mem_block_node
 {