python-telegram-bot 12.0.0b1 on Python PyPI

First beta release ever.
It has been so long since last release that we would like to test the impact before a final release.

We do NOT recommend using this beta release in production.

Major changes:

Context based callbacks
Persistence
PrefixHandler added (Handler overhaul)
Deprecation of RegexHandler and edited_messages, channel_post, etc. arguments (Filter overhaul)
Various ConversationHandler changes and fixes

See the wiki page at https://git.io/fxJuV for a detailed guide on how to migrate from version 11 to version 12.

Context based callbacks (#1100)

Use of pass_ in handlers is deprecated.
Instead use use_context=True on Updater or Dispatcher and change callback from (bot, update, others...) to (update, context).
This also applies to error handlers Dispatcher.add_error_handler and JobQueue jobs (change (bot, job) to (context) here).
For users with custom handlers subclassing Handler, this is mostly backwards compatible, but to use the new context based callbacks you need to implement the new collect_additional_context method.
Passing bot to JobQueue.__init__ is deprecated. Use JobQueue.set_dispatcher with a dispatcher instead.
Dispatcher makes sure to use a single CallbackContext for a entire update. This means that if an update is handled by multiple handlers (by using the group argument), you can add custom arguments to the CallbackContext in a lower group handler and use it in higher group handler. NOTE: Never use with @run_async, see docs for more info. (#1283)
If you have custom handlers they will need to be updated to support the changes in this release.
Update all examples to use context based callbacks.

Added PicklePersistence and DictPersistence for adding persistence to your bots.
BasePersistence can be subclassed for all your persistence needs.
Add a new example that shows a persistent ConversationHandler bot

CommandHandler now only triggers on actual commands as defined by telegram servers (everything that the clients mark as a tabable link).
PrefixHandler can be used if you need to trigger on prefixes (like all messages starting with a "/" (old CommandHandler behaviour) or even custom prefixes like "#" or "!").

RegexHandler is deprecated and should be replaced with a MessageHandler with a regex filter.
Use update filters to filter update types instead of arguments (message_updates, channel_post_updates and edited_updates) on the handlers.
Completely remove allow_edited argument - it has been deprecated for a while.
data_filters now exist which allows filters that return data into the callback function. This is how the regex filter is implemented.
All this means that it no longer possible to use a list of filters in a handler. Use bitwise operators instead!

Remove run_async_timeout and timed_out_behavior arguments (#1344)
Replace with WAITING constant and behavior from states (#1344)
Only emit one warning for multiple CallbackQueryHandlers in a ConversationHandler (#1319)
Use warnings.warn for ConversationHandler warnings (#1343)
Fix unresolvable promises (#1270)

Handlers should be faster due to deduped logic.
Avoid compiling compiled regex in regex filter. (#1314)
Add missing left_chat_member to Message.MESSAGE_TYPES (#1336)
Make custom timeouts actually work properly (#1330)
Add convenience classmethods (from_button, from_row and from_column) to InlineKeyboardMarkup
Small typo fix in setup.py (#1306)
Add Conflict error (HTTP error code 409) (#1154)
Change MAX_CAPTION_LENGTH to 1024 (#1262)
Remove some unnecessary clauses (#1247, #1239)
Allow filenames without dots in them when sending files (#1228)
Fix uploading files with unicode filenames (#1214)
Replace http.server with Tornado (#1191)
Allow SOCKSConnection to parse username and password from URL (#1211)
Fix for arguments in passport/data.py (#1213)
Improve message entity parsing by adding text_mention (#1206)

Finally fix our CI builds mostly (too many commits and PRs to list)
Use multiple bots for CI to improve testing times significantly.
Allow pypy to fail in CI.
Remove the last CamelCase CheckUpdate methods from the handlers we missed earlier.