* switching to recursive mutexes for now; easier to implement
* need to read user input from the window manager; hidden windows are
drawn when reading input from there
* note: occasional dead lock between PTY and ncurses mutex
* fixed type in class `SingleUserInput`
Some other changes to the CMake-files done as well:
* documentation looks more like Doxygen-style
* prevent mix-up with C++ GSL library ("Guidelines support library" not
"GNU scientific library")
Christian Burger