use dict.update to update config values

nhentai/cmdline.py

@@ -43,7 +43,7 @@ def load_config():
 
     try:
         with open(constant.NHENTAI_CONFIG_FILE, 'r') as f:
-            constant.CONFIG = json.load(f)
+            constant.CONFIG.update(json.load(f))
     except json.JSONDecodeError:
         logger.error('Failed to load config file.')
         write_config()

nhentai/constant.py

@@ -1,6 +1,7 @@
 # coding: utf-8
 from __future__ import unicode_literals, print_function
 import os
+import copy
 import tempfile
 
 try:
@@ -29,10 +30,10 @@ NHENTAI_HOME = os.path.join(os.getenv('HOME', tempfile.gettempdir()), '.nhentai'
 NHENTAI_HISTORY = os.path.join(NHENTAI_HOME, 'history.sqlite3')
 NHENTAI_CONFIG_FILE = os.path.join(NHENTAI_HOME, 'config.json')
 
+
 CONFIG = {
     'proxy': {},
     'cookie': '',
     'language': '',
     'template': '',
 }
-