Don't track plugin channel in nvim

During debug, the plugin should inform nvim which plugin
channel it is using.

Author: jebberjeb

plugin/socketrepl.vim.debug

@@ -1,17 +1,6 @@
-let g:is_running = 0
-let g:channel = 0
-
-"When the plugin is restarted at the repl, it reconnects, using the next
-"available channel.
-function! PluginRestart()
-    let g:is_running = 0
-endfunction
+let g:nvim_tcp_plugin_channel = 0
 
 function! StartIfNotRunning()
-    if g:is_running == 0
-        let g:is_running = 1
-        let g:channel = g:channel + 1
-    endif
 endfunction
 
 function! Connect(host_colon_port)
@@ -21,45 +10,45 @@ function! Connect(host_colon_port)
     else
         let conn = a:host_colon_port
     endif
-    let res = rpcrequest(g:channel, 'connect', conn)
+    let res = rpcrequest(g:nvim_tcp_plugin_channel, 'connect', conn)
     return res
 endfunction
 command! -nargs=? Connect call Connect("<args>")
 
 function! EvalBuffer()
     call StartIfNotRunning()
     ReplLog
-    let res = rpcrequest(g:channel, 'eval-buffer', [])
+    let res = rpcrequest(g:nvim_tcp_plugin_channel, 'eval-buffer', [])
     return res
 endfunction
 command! EvalBuffer call EvalBuffer()
 
 function! EvalCode()
     call StartIfNotRunning()
     ReplLog
-    let res = rpcrequest(g:channel, 'eval-code', [])
+    let res = rpcrequest(g:nvim_tcp_plugin_channel, 'eval-code', [])
     return res
 endfunction
 command! EvalCode call EvalCode()
 
 function! ReplLog(buffer_cmd)
     call StartIfNotRunning()
-    let res = rpcrequest(g:channel, 'show-log', a:buffer_cmd)
+    let res = rpcrequest(g:nvim_tcp_plugin_channel, 'show-log', a:buffer_cmd)
     return res
 endfunction
 command! ReplLog call ReplLog(':botright new')
 
 function! DismissReplLog()
     call StartIfNotRunning()
-    let res = rpcrequest(g:channel, 'dismiss-log', [])
+    let res = rpcrequest(g:nvim_tcp_plugin_channel, 'dismiss-log', [])
     return res
 endfunction
 command! DismissReplLog call DismissReplLog()
 
 function! Doc()
     call StartIfNotRunning()
     ReplLog
-    let res = rpcrequest(g:channel, 'doc', [])
+    let res = rpcrequest(g:nvim_tcp_plugin_channel, 'doc', [])
     return res
 endfunction
 command! Doc call Doc()

src/user.clj

@@ -14,7 +14,8 @@
 
 (defn stop
   []
-  (system/stop @system-atom))
+  (system/stop @system-atom)
+  (reset! system-atom nil))
 
 (defn reset
   []