limit what gets imported on a from x import *, and improve the docs a bit..

ntunnel/__init__.py

@@ -51,6 +51,15 @@ __author__ = 'John-Mark Gurney'
 __copyright__ = 'Copyright 2019 John-Mark Gurney.  All rights reserved.'
 __license__ = '2-clause BSD license'
 __version__ = '0.2.0.dev'
+__all__ = [
+	'ConnectionValidator',
+	'GenericConnValidator',
+	'genkeypair',
+	'parsesockstr',
+	'connectsockstr',
+	'listensockstr',
+	'NoiseForwarder',
+]
 
 _backend = default_backend()
 
@@ -678,7 +687,7 @@ def main():
 	parser_gk.set_defaults(func=cmd_genkey)
 
 	parser_serv = subparsers.add_parser('server', help='run a server')
-	parser_serv.add_argument('--clientkey', '-c', action='append', type=str, help='file of authorized client keys, or a .pub file')
+	parser_serv.add_argument('--clientkey', '-c', action='append', type=str, help='file containing authorized client key, aka a .pub file, may be specificed multiple times')
 	parser_serv.add_argument('servkey', type=str, help='file name for the server key')
 	parser_serv.add_argument('servlisten', type=str, help='Connection that the server listens on')
 	parser_serv.add_argument('servtarget', type=str, help='Connection that the server connects to')