Update documentation

The output in the examples provided in the man page hadn't been
updated as sshuttle changed its output over time.

The example of testing sshuttle without a remote host was removed. It
was the first example previously and it is something that is unlikely
users will wish to do.

Also:
 - Update some --help messages.
 - Manpage: Fix a typo.
 - Manpage: Mention that host specified with -r can be an ssh alias.
 - Eliminate variable only used once.

sshuttle/client.py

@@ -201,7 +201,7 @@ class FirewallClient:
 
     def __init__(self, method_name, sudo_pythonpath, ttl):
         self.auto_nets = []
-        python_path = os.path.dirname(os.path.dirname(__file__))
+
         argvbase = ([sys.executable, sys.argv[0]] +
                     ['-v'] * (helpers.verbose or 0) +
                     ['--method', method_name] +
@@ -224,7 +224,8 @@ class FirewallClient:
 
         if sudo_pythonpath:
             elev_prefix += ['/usr/bin/env',
-                            'PYTHONPATH=%s' % python_path]
+                            'PYTHONPATH=%s' %
+                            os.path.dirname(os.path.dirname(__file__))]
         argv_tries = [elev_prefix + argvbase, argvbase]
 
         # we can't use stdin/stdout=subprocess.PIPE here, as we normally would,

sshuttle/cmdline.py

@@ -20,7 +20,7 @@ def main():
             return 1
 
         if not opt.sudoers_filename:
-            log('--sudoers-file must be set or omited.')
+            log('--sudoers-file must be set or omitted.')
             return 1
 
         sudoers(

sshuttle/options.py

@@ -132,6 +132,7 @@ def parse_ipport(s):
 
 
 def parse_list(lst):
+    """Parse a comma separated string into a list."""
     return re.split(r'[\s,]+', lst.strip()) if lst else []
 
 
@@ -219,7 +220,7 @@ parser.add_argument(
     default=[],
     type=parse_list,
     help="""
-    capture and forward DNS requests made to the following servers
+    capture and forward DNS requests made to the following servers (comma separated)
     """
 )
 parser.add_argument(
@@ -280,7 +281,7 @@ parser.add_argument(
     action="count",
     default=0,
     help="""
-    increase debug message verbosity
+    increase debug message verbosity (can be used more than once)
     """
 )
 parser.add_argument(