Fix usage of logger constants in command system

The definition of various constants was refactored to use enumerations
in commit 2fbadc91e9. One reference in the command system was not
changed to use the new enum, however.

src/command_system/implementation/standard.py

@@ -24,7 +24,7 @@ import dialogs
 from common import gajim
 from common import helpers
 from common.exceptions import GajimGeneralException
-from common.logger import Constants
+from common.logger import KindConstant
 
 from ..errors import CommandError
 from ..framework import CommandContainer, command, doc
@@ -32,10 +32,6 @@ from ..mapping import generate_usage
 
 from .hosts import ChatCommands, PrivateChatCommands, GroupChatCommands
 
-# This holds constants fron the logger, which we'll be using in some of our
-# commands.
-lc = Constants()
-
 class StandardCommonCommands(CommandContainer):
     """
     This command container contains standard commands which are common
@@ -107,7 +103,7 @@ class StandardCommonCommands(CommandContainer):
             contact, time, kind, show, message, subject = row
 
             if not contact:
-                if kind == lc.KIND_CHAT_MSG_SENT:
+                if kind == KindConstant.CHAT_MSG_SENT:
                     contact = gajim.nicks[self.account]
                 else:
                     contact = self.contact.name