GUACAMOLE-600: Add telnet connection timeout client setting.

guacamole-ext/src/main/resources/org/apache/guacamole/protocols/telnet.json

@@ -12,6 +12,10 @@
                 {
                     "name"  : "port",
                     "type"  : "NUMERIC"
+                },
+                {
+                    "name"  : "timeout",
+                    "type"  : "NUMERIC"
                 }
             ]
         },

guacamole/src/main/frontend/src/translations/en.json

@@ -843,6 +843,7 @@
         "FIELD_HEADER_RECORDING_PATH" : "Recording path:",
         "FIELD_HEADER_SCROLLBACK"     : "Maximum scrollback size:",
         "FIELD_HEADER_TERMINAL_TYPE"   : "Terminal type:",
+        "FIELD_HEADER_TIMEOUT"         : "Connection timeout:",
         "FIELD_HEADER_TYPESCRIPT_NAME" : "Typescript name:",
         "FIELD_HEADER_TYPESCRIPT_PATH" : "Typescript path:",
         "FIELD_HEADER_TYPESCRIPT_WRITE_EXISTING" : "@:APP.FIELD_HEADER_TYPESCRIPT_WRITE_EXISTING",