app_terminal.py:  Added GATEONE_DIR to the list of variables that are passed to cmd_var_swap()
gateone.py:  Changed how the cache_dir variable is retrieved in various places.
app_terminal.py:  Changed references to the 'dtach' setting to use self.ws.settings so that it can always be overridden via the command line argument.
app_terminal.py:  new_multiplex() now logs the command it executes if logging=debug.