Since we want our bots to be both python 2 and python 3 compatible,
we use six to make up for both of them and run the bot smoothly.
'http.client' was basically used for error-handling by the author
of the bot, urllib errors can be handled by the urllib itself. So,
using this for simplicity.
urllib.request.urlopen raises URLError on protocol errors.
The zulip-run-bot script now supports passing in a --path-to-bot
option. This allows users to specify the path to the source file
for their own custom bots, the first step towards being able to
support out-of-tree bots.
To run an existing bot in the zulip_bots package, just passing in
the name of the bot should suffice.
There is no library as 'http.bot_handler'.
'http.client' is what the author of this bots initially wrote.
Searching through the git history shows that someone mistakenly
replaced 'client' with 'bot_handler' here.
get_config_info function in 'ExternalBotHandler' class was
using 2 undefined variables, which wasn't allowing bots to
access information from config file.
Fixed it, bots with api key working now.
Previously, the annotation for the (now removed)send-reply
function was also wrong, as "send-message" function of
EmbeddedBotHandler class does not return any value, contrary
to "Dict[str, Any]" as specified by the funtion.
This is done as a follow up for zulip/zulip#5842.
