Add plugins plugin to show plugged-in plugins

stdplugins/plugins.py

@@ -0,0 +1,13 @@
+"""
+Show all loaded .plugins
+"""
+from telethon import events
+
+
+@borg.on(events.NewMessage(pattern=r"\.plugins", outgoing=True))
+async def _(event): result = f'{len(borg._plugins)} plugins loaded:'
+    for name, mod in sorted(borg._plugins.items(), key=lambda t: t[0]):
+        desc = (mod.__doc__ or '__no description__').replace('\n', ' ').strip()
+        result += f'\n**{name}**: {desc}'
+
+    await event.edit(result)