This requires to add a assertion_failed_msg handler. Take this
occasion to cleanup and uniformize the various boost.cpp files that we
have.
This adds 50k line of whatever to the source code.
In particular, the directory frontends/qt4 is renamed to frontends/qt.
Many configurations file have to be updated. All mentions of qt4 in
the source have been audited, and changed to qt if necessary.
The only part that has not been updated is the CMake build system.
As discussed on the list. If no C++11 compiler is found configuration stops
with an error. There are now unneeded parts of boost, the will be removed in
a second commit.
boost::regex supports escape sequences starting with a backslash in format
strings of regex_replace, but std::regex does not. Therefore format strings
involving literal backslashes have to be written differently for both flavours.
The special MSVC handling in regex.h is removed, since it is not needed
anymore, and using grep syntax would definitely be wrong.
