SimpleMap and SimpleWriteMap
- Trivial adaptors, but they are useful in some case

Some combined maps will be reference map if the first
template parameter map is reference map or not. If I want
to give a refernce map as first map but there is a non
reference map parameter then I should wrap my first map
to a regular read-write map.

 #!/bin/bash

 cd ${0%update-libstd-tag}../doc

 mv libstdc++.tag libstdc++.tag.old

 wget http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/libstdc++.tag &&

 rm libstdc++.tag.old || mv libstdc++.tag.old libstdc++.tag