Removed engines are still in reference_settings.yml

[SmirAlex]

Engines that was already removed from searx are still in reference_settings.yml. Like www500px or searchcode. It needs to manually understand what the problem is and edit this file.

ERROR:searx.engines:Cannot load engine "www500px"
Traceback (most recent call last):
File "/mnt/c/Users/swx995135/PycharmProjects/searx/searx/engines/init.py", line 76, in load_engine
engine = load_module(engine_module + '.py', engine_dir)
File "/mnt/c/Users/swx995135/PycharmProjects/searx/searx/utils.py", line 441, in load_module
spec.loader.exec_module(module)
File "", line 779, in exec_module
File "", line 915, in get_code
File "", line 972, in get_data
FileNotFoundError: [Errno 2] No such file or directory: '/mnt/c/Users/swx995135/PycharmProjects/searx/searx/engines/www500px.py'
ERROR:searx.engines:Cannot load engine "searchcode_doc"
Traceback (most recent call last):
File "/mnt/c/Users/swx995135/PycharmProjects/searx/searx/engines/init.py", line 76, in load_engine
engine = load_module(engine_module + '.py', engine_dir)
File "/mnt/c/Users/swx995135/PycharmProjects/searx/searx/utils.py", line 441, in load_module
spec.loader.exec_module(module)
File "", line 779, in exec_module
File "", line 915, in get_code
File "", line 972, in get_data
FileNotFoundError: [Errno 2] No such file or directory: '/mnt/c/Users/swx995135/PycharmProjects/searx/searx/engines/searchcode_doc.py'
ERROR:searx.engines:Missing engine config attribute: "spotify.api_client_id"