Warn about spawn without X11 and hook

Don't fail silently. I'd prefer an actual ui notification, but in the
init the ui isn't available.

alot/commands/globals.py

@@ -230,6 +230,7 @@ def __init__(self, cmd, stdin=None, shell=False, spawn=False,
                 termcmdlist = split_commandstring(term_cmd)
                 cmd = termcmdlist + cmd
             else:
+                logging.warning('unable to handle spawn outside of X11 without touch_external_cmdlist hook set')
                 thread = False
 
         self.cmdlist = cmd