Project from UNIX branch in school 42
[✓] Manage the errors without using errno, by displaying a message adapted to the error output
[✓] Deal correctly with the PATH and the environment (copy of system char **environ)
[✓] Series of builtins: echo, cd, setenv, unsetenv, env, exit
[✓] Manage expansions $ and ˜
[✓] Manage the Ctrl-C signal
[✓] Management of execution rights in the PATH
[✓] Simple Auto completion
[✓] The separation of commands with ";"
[✓] Inhibitors (”) (double quote), (’) (simple quote) and (\) (backslash)