Add discord.Object class for generic pass-by-ID.

docs/conf.py

@@ -31,8 +31,13 @@ sys.path.insert(0, os.path.abspath('..'))
 # ones.
 extensions = [
     'sphinx.ext.autodoc',
+    'sphinx.ext.extlinks',
 ]
 
+extlinks = {
+    'issue': ('https://github.com/Rapptz/discord.py/issues/%s', 'issue '),
+}
+
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']