Pseudoshell and terminal improvements

[Nullcaller]

• Pseudoshell cursor movement
• Pseudoshell command autocompletion
• Make sure program_options.c doesn't use any options from pseudoshell.c, some common functions are probably to be moved into a common util of some sort
• Terminal-related function reorganization (Terminal-related function reorganization #12)
• Termios signal capturing (Signal capturing #4)