CMD: Win2k3 compatibility: turn the 'attrib', 'chcp', 'label' and 'replace' commands into standalone executables

Turn the 'attrib', 'chcp', 'label' and 'replace' commands into standalone executables as it is done on Win2k3 for compatibility purposes. This brings up the problem of creating a common library of functions, that I call "cmdlib", which should gather all the code common to those tools and the interpreter cmd.exe itself, concerning string display on screen, etc... Ultimately our other CLI utilities could use this library in order not to duplicate 10 times the same code.