Support for pseudo tty when launching a process

[stcarrez]

The Util.Processes package and Util.Streams.Pipes package allow to launch a process and read/write the standard input/output of the process. When launched and having the standard output redirected to a pipe, most Unix processes will bufferize their output making reading their output less interactive.

The pseudo tty mode allows to create a pseudo tty instead of a traditional pipe so that the launched process thinks it is running within an interactive terminal and it does not bufferize its output.

Possible settings:

Pipe    : aliased Util.Streams.Pipes.Pipe_Stream;
...
    Pipe.Set_Allocate_TTY (True);