ssh kitten: Start work on connection sharing

Basic sharing works. Now investigate if we can eliminate the round-trip
latency by transmitting the data without waiting for the start message
when using a shared connection

kittens/ssh/options/definition.py

@@ -79,6 +79,12 @@ value are expanded. The default is empty so no changing is done, which
 usually means the home directory is used.
 ''')
 
+opt('share_connections', 'y', option_type='to_bool', long_text='''
+Within a single kitty instance, all connections to a particular server can be
+shared. This reduces startup latency for subsequent connections and means that you have
+to enter the password only once. Under the hood, it uses SSH ControlMasters and
+these are automatically cleaned up by kitty when it quits.
+''')
 
 opt('interpreter', 'sh', long_text='''
 The interpreter to use on the remote host. Must be either a POSIX complaint shell

kittens/ssh/options/parse.py

@@ -2,7 +2,7 @@
 
 import typing
 from kittens.ssh.options.utils import copy, env, hostname, relative_dir
-from kitty.conf.utils import merge_dicts
+from kitty.conf.utils import merge_dicts, to_bool
 
 
 class Parser:
@@ -30,6 +30,9 @@ class Parser:
     def remote_dir(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         ans['remote_dir'] = relative_dir(val)
 
+    def share_connections(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
+        ans['share_connections'] = to_bool(val)
+
     def shell_integration(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         ans['shell_integration'] = str(val)
 

kittens/ssh/options/types.py

@@ -12,6 +12,7 @@ option_names = (  # {{{
  'interpreter',
  'login_shell',
  'remote_dir',
+ 'share_connections',
  'shell_integration')  # }}}
 
 
@@ -21,6 +22,7 @@ class Options:
     interpreter: str = 'sh'
     login_shell: str = ''
     remote_dir: str = '.local/share/kitty-ssh-kitten'
+    share_connections: bool = True
     shell_integration: str = 'inherited'
     copy: typing.Dict[str, kittens.ssh.copy.CopyInstruction] = {}
     env: typing.Dict[str, str] = {}