Rename fmfuncs -> core (cleaner, semantic)

plugins/example_plugin/__init__.py

@@ -9,7 +9,7 @@ import json
 
 # 导入命令装饰器
 try:
-    from fmfuncs.plugin_command_decorator import plugin_command, command
+    from core.plugin_command_decorator import plugin_command, command
 except ImportError:
     # 回退方案
     def plugin_command(name=None, description=None, permissions=None):